When Brock Lesnar Superplexed him from the top turnbuckle, and the ring collapsed (it was rigged that way, but STILL!....)
Done again with Mark Henry which was just as awesome, if not more awesome than the Brock Lesnar superplex.
And then there was his match with Shane McMahon, where he fell off the Titan Tron and fell more than thirty feet to the arena floor. Shane then proved to be just as ballsy as his old man by jumping down after him for the pinfall.
This narrowly beat out what could have been another crowning moment a few moments earlier, when Big Show hit Khali with a flawlessly executed running spear that allowed for an instant pin. Seeing someone as big as Show flying through the air like that was damned impressive.
How about being only the third man to hold the WWE, World Heavyweight and ECW Championships? (The first being Kane and the second being CM Punk).
Even better he is the first and only man to hold those and the WCW title.
While the WWE incarnation of ECW is generally considered to be better left forgotten, Show's run was actually a highlight, at least initially, where - to build up credibility of the ECW championship, he had a series of PPV quality matches with the likes of Ric Flair, Kane, The Undertaker, DX, and Batista, practically on a weekly basis.
Winning the Intercontinental Championship from Cody Rhodes at WrestleMania 28, his first ever solo win at Wrestlemania, and becoming the 12th Grand Slam Champion. Wrestlemania moment indeed!
Also he is the third man after Edge and Kurt Angle to have held all of the currently active titles.
Given that, due to some of the belts being permanently retired, there are only four active wrestlers left that could possibly accomplish the feat (those being The Undertaker, William Regal, Mark Henry, and R-Truth... yes, you read that right), all four of them are over 40 and the only one that works a full-time schedule is the least likely to do it (R-Truth, who needs a World and the IC title and has been largely a career midcarder), Show may well be the last one to accomplish the feat unless one of the retired titles is brought back or the rules are changed.
In 2002, he once threw Rey Mysterio about five rows into the audience, an impressive feat even though he was a heel.
Responding to chants of "You can't wrestle!" by chanting back in EXACTLY the same rhythm "I don't have to!"
10/07/13 Monday Night RAW: After spending a month+ being little more than a chained dog for "TheAuthority," The Big Show is fired for having knocked out everyone in the previous night's championship match, ending it in a no-contest. The Big Show, however, refused to go quietly. After the last match, when The Shield was doing their usual post-match beat down on their opponents, The Big Show's music hit and he came out, with a purposeful stride that sent Triple H scurrying behind The Shield. As he entered the Ring, the Shield attacked, beating him down. Triple H got brave again, took his jacket off, and ordered the Shield to finish him off. However, as The Shield was lifting him up, The Big Show roared back to life, launched all three members of the Shield out of the ring and leaving him alone with Triple H. One KO Punch later, The Big Show is walking away, leaving Triple H prone in the ring. As Michael Cole said, "There is nothing more dangerous than a desperate man with nothing to lose."
Not to mention Big Show's absolute Genre Savvy shit-eating grin the entire time. He knew the moment he KO'ed Armstrong and cost Orton the title that Stephanie would be all over him about it. He knew that calling her and Triple H out would not only piss her off, but that completely no-selling her Bitch Slap and verbal spites would lead her to fire him out of frustration, freeing him up for an much overdue Roaring Rampage of Revenge. He was Genre Savvy to not try and get back into the building until after Triple H thought he'd be long gone, in all likelihood dispatched whatever "security" JBL was hoping for, then hit the stage, bulldozing through the Shield with relative ease and taking all of five seconds to decide whether or not to KO his boss who has all but stated that he owns Show. During all of this (except during the brief Shield beatdown) Show never once stopped smiling because...he knew.
Appearing out of the crowd during the Rhodes' match against The Shield for the tag team titles, taking all three of the weakened hounds out by himself, and hurling the legal man back in the ring so Cody can pin him. He then leads the crowd in a YES! chant, mirroring Daniel Bryan doing the same after the above incident. It might be safe to say they're even for him knocking out their dad weeks ago.
And this is another instance of The Big Show's Genre Savviness. The Authority had made this match no-DQ so that the Shield would have free reign to punish the Rhodes Brothers. This also means that there was nothing that could be done to stop the Big Show once he jumped the barricade. When it's all said and done, Triple H can only fume in the ring, stuck with the knowledge that the Big Show ensured that Trips was Hoist by His Own Petard.
How he got his job back. He sued the Authority for wrongful termination and for forcing him to be their minion. That's right, Big Show weaponizedReality Ensues.
His manhandling of Brock Lesnar in January 2014. After Brock broke Mark Henry's arm, Big Show decided he'd had enough of Brock's crap and stalked down to the ring in full Tranquil Fury mode. When Lesnar backed out of the ring only to try to ambush Show from behind, Show choked him into the corner, and then bodily pitched Brock Lesnar halfway across the ring.