VIDEO: The Big Bang Theory Bazingas The Comic-Con Crowd With Surprise Guests Johnny Galecki, Melissa Rauch And Stephen Hawking At Writers' Panel

It was one Bazinga! after another at the Friday, July 19, panel for The Big Bang Theory at Comic-Con: International San Diego. For the first time ever, fans were invited into a virtual Writers' Room with the hit show's executive producers and writers for a lively discussion about the genius comedy's creative process. The experiment: Put seven funny writers and a funny-in-a-theoretical-kind-of-way science consultant in front of a costumed audience and see what can result.

• The first surprise occurred during the panel's introduction, when the show's sixth-season highlight reel was kicked off with a personal welcome from world-renowned author/physicist Stephen Hawking. In a pre-recorded video segment shot in his Cambridge office, Hawking greeted Comic-Con fans and - in his own inimitable, self-deprecating way - cleared up any confusion about our universal origins by covering the actual "Big Bang" theory in only 17 words!
• One surprise followed another as the panel's usual journalist moderator was supplanted by none other than series star Melissa Rauch, who plays the spirited microbiologist Bernadette Rostenkowski-Wolowitz, newly married to astronaut/engineer Howard Wolowitz (star Simon Helberg).
• With the crowd still abuzz, the creative panel took a question from an insistent costumed fan, dressed up in authentic Star Wars regalia as the fully masked Ubese bounty hunter "Boushh," whose outfit Princess Leia used as a disguise in Return of the Jedi. Upon insistence from the panel, the costumed questioner was unmasked to reveal (surprise!) series star Johnny Galecki, who plays Leonard Hofstadter. Galecki joined the panel for the remainder of the session. Not revealed: whether Galecki was also wearing Princess Leia's metal bikini!

Click below to see The Big Bang Theory season 6 highlight reel

• In addition to Rauch, Galecki and Hawking, The Big Bang Theory Comic-Con panel also featured executive producer/showrunner Steve Molaro and co-creator/executive producer Bill Prady; co-executive producers Dave Goetsch, Steve Holland, Eric Kaplan and Jim Reynolds; supervising producer Maria Ferrari and science consultant David Saltzberg.
• From Chuck Lorre Productions, Inc. in association with Warner Bros. Television, The Big Bang Theory airs Thursdays at 8/7c on CBS, with season 7 premiering on September 26. Warner Home Video will release "The Big Bang Theory: The Complete Sixth Season" on Blu-ray and DVD on September 10.