Every WrestleMania has had at least one signature moment... sure, some Manias are remembered more fondly than others, others deserved to be panned, but none have been completely forgotten. Here, I'll try to capture the highlights, flavor, (and maybe a few personal reminisces) of each event, in easy-to-read bullet form.
 

Here are some of the highlights of the first 20 years of "WrestleMania."

WrestleMania
Capped off with Hulk Hogan and Mr. T vanquishing the evil duo of Roddy Piper and Paul Orndorff, this event also featured Andre the Giant beating Big John Studd in a bodyslam challenge match, the hated tag team of the Iron Sheik and Nikolai Volkoff winning the WWF Tag Team Titles from Barry Windham and Mike Rotundo, and King Kong Bundy squashing SD Jones in 9 seconds. Celebs in attendance included Cyndi Lauper (who managed Wendi Richter to a Ladies' Title victory over Lelani Kai), Muhammad Ali (who was a guest ref for the main event), Billy Martin, Liberace, and the Rockettes.
(READ THE OOLD TYME RASSLIN' REVUE FOR WM1)

WrestleMania 2
The only wrestling event to ever emanate from three separate venues, the second WrestleMania saw Hulk Hogan emerge victorious from a bloody cage match against King Kong Bundy. At other venues, highlights included Andre the Giant winning a 20 man Battle Royal (that featured many NFL stars), the British Bulldogs winning the WWF Tag Team titles from the Dream Team, and Mr. T getting a disqualification win over Roddy Piper in a boxing match. Notable celebs included Ozzy Osbourne (who is obviously the coolest celeb ever at WrestleMania, and has been referred to as such here in the OO Road to WM since LONG before "The Osbournes" ever got famous), Tommy Lasorda, Elvira, and the "Where's the Beef?" lady.
(READ THE OOLD TYME RASSLIN' REVUE FOR WM2)

WrestleMania III
WrestleMania may well have peaked in its third year, drawing a record indoor crowd to watch Hulk Hogan bodyslam and pin the seemingly unbeatable Andre the Giant. This show also featured what is widely regarded as one of the greatest matches since the advent of PPV, as Ricky Steamboat won the InterContinental Title from Randy Savage. Although he remained active for nearly another 15 years, Roddy Piper  "retired" from wrestling after beating the late Adrian Adonis at this event. Celebs of note included Alice Cooper, Bob Uecker, and Mary Hart.  This was my first live WrestleMania, as I was finally deemed old enough to handle the violence by my mom, and even got her to drive me to watch the show on closed-circuit TV; Steamboat/Savage was so intense, I actually bruised by hand POUNDING on the metal railing in front of me!
(READ THE OOLD TYME RASSLIN' REVUE FOR WM3)

WrestleMania IV
The WWF Title was up for grabs in a 14-man tournament. In a second-round battle of favorites, Hulk Hogan and Andre the Giant went to a double disqualification, eliminating both men from contention. In the eventual final, Randy Savage got help from Hulk Hogan, and defeated Ted DiBiase to begin his first reign as WWF champ. Demolition began their domination of the WWF tag scene at this show as well, winning their first titles by beating Strike Force. Bob Uecker was back again for this 'Mania.  At four hours long, this event held the PPV duration record until the WWF started intentionally booked 4 hours of satellite time for WrestleManias starting in 2000.
(READ THE OOLD TYME RASSLIN' REVUE FOR WM4)

WrestleMania V
The "explosion of the Mega Powers" took place at this event, as Hulk Hogan and Randy Savage tossed aside a successful year of teaming up to battle for Savage's WWF Title in the main event. Hogan walked away the new champ, beginning his second reign. Highlighting the undercard was Rick Rude's win over the Ultimate Warrior to become the IC champ. Roddy Piper made a non-wrestling return to the WWF here, hosting a special Piper's Pit, and humiliating Brother Love and Morton Downey Jr. in the process.
(READ THE OOLD TYME RASSLIN' REVUE FOR WM5)

WrestleMania VI
The Ultimate Warrior stepped to the head of the class, eclipsing Hulk Hogan in the "title vs. title" main event of WM6 to take over the reigns of the WWF. The match, between two men not usually well regarded for their ring skills, still ranks among the most memorable and dramatic of all time. Also at this show -- which filled up the Toronto SkyDome -- Roddy Piper proved retirement can be temporary by returning to brawl against Bad News Brown. Steve Allen was among the celebs to turn out for the show.
(READ THE OOLD TYME RASSLIN REVUE FOR WM6)

WrestleMania VII
Playing off the recently-ended Gulf War, the "Real American" Hulk Hogan topped off one of the more embarrassing feuds in WWF history by defeating "Iraqi sympathizer" Sgt. Slaughter to regain the WWF Title in WM7's main event. Randy Savage, following in Roddy Piper's footsteps, also wrestled in a meaningless "retirement" match, losing to the Ultimate Warrior. This 'Mania also saw the end of the original Hart Foundation, as Bret Hart and Jim Neidhart lost the WWF tag titles, and moved into singles action. Willie Nelson was chief among the celebs in attendance.  On a personal note, this is the only WM besides the first two that I did not see "in real time" -- either in person, on closed circuit, or on PPV... unlike the first two, the reason was simple availability and not my inability to attend closed circuit telecasts without parental assistance; with this Mania, the Closed Circuit Era was dead, and full PPV penetration in Dayton was still almost a year away.
(READ THE OOLD TYME RASSLIN REVUE FOR WM6)

WrestleMania VIII
The third "dome" WrestleMania, this show featured a double main event. For starters, Randy Savage toppled Ric Flair (making his first WM appearance, and the only one that could be said to have been near his "prime") to win the WWF Title for a second time. Closing out the show, Hulk Hogan settled for a DQ win over Sid Justice when Papa Shango interfered; the Ultimate Warrior made a shocking return to the WWF to save Hogan. Also on the show, Bret Hart won his second IC Title, beating Roddy Piper. This WM also marked the beginning of Shawn Michaels' post-Rockers singles career, as he handed Tito Santana his seventh consecutive WM loss.  I was there in person in Indianapolis, making this my only live WM.  It is also the only WM that I have never seen the PPV broadcast of, with the exception of the clips that have been included in various WM retrospectives over the years.  Savage/Flair was awesome, why haven't I ever gotten my hands on a tape of this one?
(READ THE OOLD TYME RASSLIN REVUE FOR WM8)

WrestleMania IX
Yokozuna made history on this night, as the only man ever to win the WWF Title and lose it via pinfall in the very same night. In the scheduled main event of the show, Yoko pinned Bret Hart to win the strap; less than two minutes later, Yoko was pinned by Hulk Hogan in an unscheduled, but sanctioned, match. Earlier on the show Hogan had teamed with Brutus Beefcake in an unsuccessful attempt to win the WWF Tag Titles from Money, Inc. This is widely regarded to be one of the least entertaining Manias....  yet, in one of my more shameful displays, I felt so strongly attached to my newfound role as "WWF Cheerleader" on a newsgroup called RSPW (which I had just discovered a few months prior) that I found it necessary to strongly praise the show in a debate versus the Immortal Herb Kunze.  Ouch.  I take it back. 
(READ THE OOLD TYME RASSLIN REVUE FOR WM9)

WrestleMania X
After a "tie" at the Royal Rumble, both Lex Luger and Bret Hart were scheduled to receive WWF Title shots at this 'Mania. Luger failed in his attempt, losing to Yokozuna. But Bret Hart rebounded from a loss to his brother Owen (in a fantastic show-opener) to defeat Yoko, as both men were wrestling their second match of the night, to win his second WWF Title. However, stealing the show was another of the Great WrestleMania Matches of All Time, as Razor Ramon topped Shawn Michaels in a Ladder Match for the IC Title. Burt Reynolds was among the celebs tapped to appear on the show; he may not have been totally sober.  Which is OK, because this was also the first WM for which I was not totally sober; and so a whole NEW WM tradition began!
(READ THE OOLD TYME RASSLIN REVUE FOR WM10)

WrestleMania XI
Lawrence Taylor made sports page headlines when he faced Bam Bam Bigelow in one of the co-main events of the eleventh 'Mania. LT won the match, as he was seconded by an "All Pro" squad (including former WCW star -- and former husband of one-time WWF Diva Debra -- Steve McMichael) and serenaded by Salt 'n' Pepa. Surprisingly, the match did not suck.  In the other marquee contest, Diesel retained the WWF Title, beating Shawn Michaels. Both Bigelow and Michaels would turn babyface in the near future.  Roddy Piper made a second consecutive guest ref appearance at WM11, and other special guests included Playmates Pam Anderson and Jenny McCarthy, as well as Nick Turturro.
(READ THE OOLD TYME RASSLIN REVUE FOR WM10)

WrestleMania XII
One of the truly memorable 'Manias, #12 saw Shawn Michaels defeat Bret Hart nearly 65 minutes into an "Ironman" match to win the WWF Title. Neither man dropped a fall in 60 minutes of action, and the match progressed to overtime. In another unforgettable affair, Roddy Piper and Goldust brawled in a Hollywood backlot before the battle moved to the Anaheim Pond, where bloodied Piper finally beat and defrocked Goldust. WM12 also marked the beginning of the Ultimate Warrior's short-lived return to the WWF, as he beat the debuting Hunter Hearst Helmsley in rather humiliating fashion (needless to say, it wasn't long before Triple H was no longer on Squash Duty).
(READ THE OOLD TYME RASSLIN REVUE FOR WM12)

WrestleMania 13
Nearly six years after he first pinned Hulk Hogan to become the WWF champ, the Undertaker finally made good on an opportunity to regain that coveted strap, beating Sid in the title match main event of this show. But the only match from the thirteenth 'Mania that people still actually talk about is Bret Hart and Steve Austin's Submission Match. The two men reversed roles in the course of the match, as Austin -- despite being badly bloodied and a loser in the match -- was treated to a standing ovation by the crowd while Bret was booed after the match.  An awesome match on an otherwise dreadfully lacking edition of WrestleMania.
(READ SCOTT KEITH'S FULL RETRO RANT FOR WM13)

WrestleMania XIV
Without a doubt, the big story at the fourteenth WrestleMania was the participation of boxing mega-star Mike Tyson in the main event.  Tyson, who had masqueraded as a member of the Shawn Michaels-led Degeneration X, turned on Michaels in the main event world title match, assisting Stone Cold Steve Austin in gaining his first WWF Title in front of an ecstatic crowd.  Also on the show:  the Undertaker continued his winning ways at WM by settling a six month-long feud with his newly-unearthed brother Kane, while Rocky Maivia made his second successful IC Title defense in as many WM appearances and also finalized his full transformation into "The Rock."  Pete Rose and Gennifer Flowers were among other non-Tyson celebs on hand.
(READ SCOTT KEITH'S FULL RETRO RANT FOR WM14)

WrestleMania XV
Back at WM15, the Rock was enjoying his final days as a hated heel...  it was at that show that he was struck down by the beloved Steve Austin, as Stone Cold won the WWF Title in the WM main event for the second consecutive year.  While the Undertaker and Big Bossman soiled the Hell in the Cell gimmick with a plodding affair, the undercard was spruced up by the near in-ring assassination of Bart Gunn by Brian "Butterbean" Esch in a brutal Brawl For All match.  The show also saw the PPV wrestling debut of Shane McMahon as well as a a heel turn for Triple H that certainly paid dividends over the next two years.  Also of note:  Pete Rose returned to WrestleMania for the second consecutive year, and was Tombstoned by Kane for the second consecutive.
(READ SCOTT KEITH'S FULL RETRO RANT FOR WM15)

WrestleMania 2000
For the first time since the original WrestleMania, the main event at the Granddaddy of 'em All featured more than two men.  And for the fist time ever, a heel won said main event.  In a four corners match, Triple H made WWF history by retaining his WWF Title over the Rock, Mick Foley, and the Big Show.  But the show was stolen by the undercard, which featured the strongest "debuting class" of talent EVER at a WrestleMania:  WM rookies Chris Benoit, Chris Jericho, and Kurt Angle battled for the "EuroContinental" title, while fellow rooks the Dudleys, Hardys, and Edge/Christian waged war in a wild Tables and Ladders match.  And again, Pete Rose appeared and made another (futile-but-hilarious) attempt to avenge himself upon Kane.
(READ SCOTT KEITH'S FULL RETRO RANT FOR WM16)

WrestleMania X-7
Nine years after the WWF last used a dome for WM, nearly 70,000 fans packed the Houston AstroDome for what was immediately hailed by fans as an Instant Classic.  The undercard itself was stellar, featuring: (1) the Hardys, Dudleys, and Edge/Christian wowing fans for the second straight year, (2) a surprisingly high-spot-laden Sports Entertainment Segment between Shane and Vince McMahon, (3) a technical masterpiece between Kurt Angle and Chris Benoit, and (4) the Undertaker's best WM match ever, as he defeated Triple H.  But the main event stole the headlines as Steve Austin took the WWF Title from the Rock, but shockingly turned heel in the process, marking the second consecutive year a heel left Mania with the big strap.
(READ SCOTT KEITH'S FULL RETRO RANT FOR WM17)

WrestleMania X-8
The weak story-telling leading into many of WM18's top matches is long forgotten, leaving us to remember the show for Hulk Hogan's return to the business' biggest stage.  Hogan faced the Rock in his first Mania match in 9 years, and had the Toronto SkyDome crowd in the palm of his hand.  Hogan, though still ostensibly a heel, was a huge sentimental favorite during a match that was far more entertaining than anyone could have guessed. Rock won, but Hogan was the star of the night, and was propelled into his final babyface run as a result.  Other matches on the final WM PPV of the WWF era: Triple H (briefly experimenting as a babyface) beat Chris Jericho for the Undisputed Title in the anti-climax to a feud that could not have been mishandled any worse, Rob Van Dam won the IC belt from William Regal, and Undertaker's tenth win in ten WM matches (over Ric Flair, who lost his second in two tries).  
(READ RICK SCAIA'S RECAP OF WM18)

WrestleMania XIX
WMXIX brought the Granddaddy of 'em All back to its old glory with a line-up that featured almost a half-dozen very-well-hyped main event caliber contests.  A shocking run-in by Roddy Piper highlighted a surprisingly entertaining Vince McMahon vs. Hulk Hogan match, while Shawn Michaels and Chris Jericho stole the show with an outstanding old school wrestling match.  And in the main event, Brock Lesnar won his second WWE Title from Kurt Angle, but not before a breath-taking "Holy Shit Moment" in which he nearly broke his neck on an attempted Shooting Star Press.  Also of note: The Rock beat Steve Austin in the pair's third time facing each other at a WM event, Trish Stratus won the Women's Title in a four-way match, Matt Hardy retained the Cruiserweight Title from Rey Mysterio, HHH retained the World Title over Booker T, fans endured two Limp Bizkit performances (while Ashanti and the Miller Catfight Girls supplied the only other star power), and WWE announced the impending arrival of Bill Goldberg.
(READ RICK SCAIA'S RECAP OF WM19)

WrestleMania XX
Probably one of the greatest Feel Good Moments in WM History took place at WM20, as Chris Benoit and Eddie Guerrero celebrated together to close out the show, each the champion of his respective brand. Desire and talent won out over the conventional wisdom that wrestling is a Big Man's game... well, it won out for about 3 months at least; but at WM20, fans had no idea just how short-lived Benoit and Eddie's reigns would be. Bolstering those top two title matches: the memorable Jericho vs. Christian climax of the RAW Love Rhombus (in which Trish Stratus completed a surprising heel turn), the eyeball-riveting trainwreck of a match that was Goldberg vs. Lesnar, Molly Holly getting her head shaved for the good of the company, and a flat-out entertaining-as-hell Rock 'n' Sock Connection vs. Evolution tag match. Notable from WM20: the total absence of outside celebrities... wrestling legends and Hall of Fame inductees were the Special Guests on this night (save for a brief ringside cameo by Donald Trump), and the spotlight was put squarely on those who take (or took) care of their business inside a wrestling ring. 
(READ RICK SCAIA'S RECAP OF WM20)

What will be the memories we take away from the twentieth installment of WrestleMania? We'll find out soon enough....