Chiat/Day co-founder Guy Day.

Guy Day, a creative director who, with advertising executive Jay Chiat, founded the ad agency Chiat/Day, died peacefully in his sleep from natural causes on Saturday. He was 77.

Day was originally the founder of Los Angeles-based agency Day/Faust. When his business partner Tom Faust departed, he met with Chiat at a Los Angeles Dodgers game to discuss a new venture. The two men worked out a deal to merge their agencies to create Chiat/Day during the game's sixth inning and the agency opened in 1968.

Shortly after its launch, Day famously told a reporter from The Los Angeles Times that he stepped into the role of president following a coin toss.

"Nobody was ever really sure whether being named president was the result of winning, or losing the coin toss," TBWA\Chiat\Day CMO Laurie Coot wrote on the agency's alumni blog Tuesday. "But it set the stage for the total distaste for hierarchy and any trace of organizational politics."

Day sold his holdings and left the agency in the late 1970s to focus on his family and personal pursuits but rejoined in 1981. During that time, Chiat moved to New York and Day headed up operations in Los Angeles. He left the agency for good in 1986 and in 1995, Chiat/Day joined with TBWA to form TBWA/Chiat/Day, creating an international agency with 58 offices in more than 40 countries worldwide.

"Guy made me sane while Jay made me crazy," said Lee Clow, chief creative officer and global director of Media Arts, TBWA Worldwide. "He taught me a lot of things - like how to understand Jay. I probably wouldn't be here if it weren't for Guy."

Day is survived by his wife Annette, daughter Colleen, sons Bill and Cameron and four grandchildren. A private family ceremony will be held through the Neptune Society.

To read tributes by friends and colleagues, visit the Chiat\Day alumni blog, jayday.org