After some discussion about it on Sunday in the Survivor Series live thread, here is (what I believe to be) the complete list of Big Show face/heel turns. Sadly, done mostly from memory.
The Giant/Big Show Face-Heel Turns. · 1995 – Starts out as a heel in the Dungeon of Doom. · July/August, 1996 – Becomes a de facto face in the WCW v. nWo feud as World Champion, feuding with and losing the WCW Title to “Hollywood” Hogan. · September, 1996 – Joins nWo, turns heel against WCW. · December, 1996 – Turns face against the nWo, rejoins WCW to feud with Hogan and The Outsiders. · May, 1998 – Turns against WCW, joins the nWo Hollywood faction. Feuds with Sting, Kevin Nash. · January 1999 – When the nWo reforms, gets dumped by the Hollywood faction and beaten by Kevin Nash who becomes the “Giant” of the nWo. Debuts in WWF/E. · February 14, 1999 – Debuts at St. Valentine’s Day Massacre as part of Vince McMahon’s corporation, definitely as a heel. Starts to rub the Rock the wrong way though. · March 25, 1999 – Punches Vince McMahon in the face at the end of his match v. Mankind, becomes babyface and joins the U.N.I.O.N against Shane McMahon. · July, 1999 – Forms heel team with Undertaker against the tag champions Kane & X-Pac, beating them at Summerslam for the belts and losing them to the Rock & Sock Connection. · October, 1999 – Undertaker injury leaves Show directionless, starts angle with Boss Man over dying father to become a babyface again. Beats HHH to win the WWF Title to cement the face turn at Survivor Series. · January, 2000 – Takes offense to the Rock calling people “jabronies,” becomes heel again. Aligns himself with Shane McMahon. · April, 2000 – Becomes happy-go-lucky face the night after WrestleMania. Feuds with Kurt Angle and Shane McMahon. Does an injury angle in May 2000. · July,2000 – Returns from injury and turns heel to feud with a now babyface Undertaker, but is almost immediately sent to OVW to lose weight. · January 2001 – Returns at the 2001 Royal Rumble, still a heel. Feuds with Rock and Kane. · July 2001 – Becomes a babyface when the WWE v. Alliance feud takes over the storylines. Aligned with the WWF, against the Alliance. · May, 2002 – Turns heel, aligns with Ric Flair over snub of not being on the WrestleMania X-8 card. · October 2002 – Heels on Eric Bischoff because his talents are being wasted on Raw, gets traded to Smackdown as a result. · October 2002 – Arrives on Smackdown as a babyface and goes heel immediately, taking out the Undertaker and beating Brock Lesnar in a heel v. heel match for the WWE Title (Heyman turns and joins Big Show, turning Brock babyface). This is a pretty prolific heel run, contending for the World title on multiple ppvs, feuding with the Undertaker, winning the US title and starting his never-ending feud with John Cena. This run ended when in April 2004 he lost a loser gets fired match to Eddie Guerrero and threw Kurt Angle off a ledge or something. · September 2004 – Returns to Smackdown to feud with heel GM Kurt Angle, making him a babyface. Stays a babyface through a feud with Angle, JBL, and Carlito before being drafted over to Raw in 2005. Teams with Kane to win tag titles. · July 4, 2006 – Gets drafted to ECW and turns heel, aligning with Paul Heyman and beating RVD for the ECW Title. Stays heel for the end of this run until December to Dismemeber in 2006 when he loses the World Title to Bobby Lashely. Big Show leaves the company in December 2006 and is out until No Way Out, February 2007. · Returns at No Way Out as ostensibly a babyface, then goes heel in Floyd Mayweather confrontation. Show wrestled mostly as a heel, but the face/heel dynamics in the Mayweather feud changed seemingly weekly, ending at Mania 24 with Big Show getting most of the babyface heat at Mayweather most of the heel heat. I think. · Definitely a face after WrestleMania 24, feuding with the Great Khali. · September 2008 – Turns heel against the Undertaker, aligns with Vicki Guerrero. Some pretty good heel moments here, including his affair with Vicki and tag teams with Chris Jericho (“Jeri-show”) and The Miz (“Show-Miz”). · April 2010 – Turns on Miz after losing the belts to the Hart Dynasty, becoming a face and moving to Smackdown. Feuded with World Champion Jack Swagger and CM Punk’s Straight Edge Society, and into 2011 had a pretty great feud with Mark Henry.· June, 2012 – Gets fired by Johnny Laurenitis on a Monday and turns heel on John Cena the following Sunday. Pretty effective heel run here, winning the World title and dropping it to the bland Alberto Del Rio, making him an interesting face for a bit. · March/April 2013 – Aligns himself with faces Sheamus & Randy Orton to fight the Shield, then turns on them after a losing effort at WrestleMania 29. · September, 2013 – Becomes a whipping boy for “The Authority,” doing bad things because he had no choice. Turns face and feuds with Orton. · November, 23, 2014 – Turns heel against John Cena and joins the Authority; issues a “mea culpa” to the fans that goes unaccepted and remains a heel.
I believe the actual number was calculated to be 32 by the uber-nerds of the wrestling world, so you're actually a few short here, believe it or not. Mind-blowing, I know. Makes Lex Luger look like a stable personality.