I was curious about this subject and did a little research on the old interweb. This is the biggest list I found:
‘Superstar’ Billy Graham - 585
BRAWK! Lesnar - 475
Eddie Guerrero - 275
Taz - 450
‘British Bulldog’ Davey Boy Smith - 550
Doug Furnas - 600
Scott ‘Flash’ Norton - 650
‘H2O’ Ron Waterman - 500+
Bruno Sammartino - 565
The Ultimate Warrior - 500
Road Warrior Animal - 550
‘Superfly’ Jimmy Snuka - 525 (in his bodybuilding days, before he became a wrestler)
Sting - 365
Chyna - 310 (she once claimed she could bench 375, but looking at other female lifters, I find that HIGHLY unlikely)
Kurt Angle - 420
‘relliK’ Johnny Stamboli - 495
Bill Kazmaier - 660
Tony ‘Ludwig Borga’ Halme - 600
‘Total Package’ Lex Luger - 530
Bulldog Brower - 500
Bryan ‘Crush’ Adams - 585
‘The Big Show’ Paul Wight - 500 (when challenged in the weights room - he did it without too much apparent effort and didn’t bother going any higher)
Dino Bravo - 570
Chris Benoit - 450
Shane Douglas - 420
The Barbarian - 550 for 3 reps (no pause)
Iron Sheik - 345
Tank Abbott - 600
Bret ‘The Hitman’ Hart - 415
‘Big Bully’ Nick Busick - 605
Nikolai Volkoff - 600+
Ole Anderson - 405
Dynamite Kid - 450
Ted Arcidi - 700
Reggie Lisowski - 500
‘Polish Power’ Ivan Putski - 600
‘Ravishing’ Rick Rude - 405 for 3 reps (no pause)
Skandor Akbar - 500
The Rock - 425
Batista - 525
Ahmed Johnson - 520
Chris Candido - 400+
The Warlord - 575 for 6 reps (no pause)
Road Warrior Hawk - 515
‘Lethal Weapon’ Steve Blackman - 550 (in his weightlifting days, before wrestling)
Bill Goldberg - 495 for 5 reps (but has claimed in interviews that he only does 400)
Triple H - over 400 (no figure stated beyond that)
Scott Steiner - 525 (he claimed he could do over 600 in the dying days of WCW BUT Steiner was heavily into kayfabe back then and had stated in previous interviews that he avoided the benchpress where possible, owing to injuries)
Austin Idol - 505
Jim ‘The Anvil’ Neidhart - 550 (with ease and just fooling around)
Mark Henry - 620
Magnum TA - 350 (for 10-12 reps)
Hulk Hogan - 550
Kevin Sullivan - 350
‘Nature Boy’ Ric Flair - 500 (in his days as a 280lb powerlifter before his plane crash)
Mike Graham - 440
Tony Atlas - 600
‘Cowboy’ Bill Watts - 500
Steve Keirn - 425
The Crusher - 500
Bill ‘Ax’ Eadie - 450 (estimated)
Jos LeDuc - 600
Kane - 405 (for sets - no max recorded)
Obviously, guys like Kazmaier have their maxes on record, but I wanted to see what people thought about some of the others. I immediately dismissed the numbers for Steiner, Goldberg, and Hogan, but a lot of these guys are way before my time.