William Ernest "Bill" Walsh (November 30, 1931 – July 30, 2007) was an American head football coach of the San Francisco 49ers and Stanford University, and popularized the West Coast Offense. Walsh went 102-63-1 with the 49ers, winning 10 of his 14 postseason games along with six division titles. He was named the NFL's coach of the year in 1981 and 1984.

Early career
Walsh began his pro coaching career in 1966 as an assistant with the AFL's Oakland Raiders. As a Raider assistant, Walsh was groomed in the vertical passing offense of Sid Gillman, favored by Al Davis. Walsh would later modify his own offensive philosophy to favor a predominantly horizontal passing approach.
He then moved to the AFL expansion Cincinnati Bengals in 1968, serving under Paul Brown for seven seasons as one of the architects of the team's offense, built around quarterback Ken Anderson and wide receiver Isaac Curtis.
When Brown retired as head coach following the 1975 season and appointed Bill "Tiger" Johnson as his successor, Walsh resigned and served as an assistant coach for Tommy Prothro with the San Diego Chargers in 1976. In a 2006 interview , Walsh claimed that during his tenure with the Bengals, Brown "worked against my candidacy" to be a head coach anywhere in the league. "All the way through I had opportunities, and I never knew about them," Walsh said. "And then when I left him, he called whoever he thought was necessary to keep me out of the NFL."
In 1977, Walsh was hired as the head coach at Stanford where he stayed for two seasons. His two Stanford teams went 9-3 in 1977 with a win in the Sun Bowl, and 8-4 in 1978 with a win in the Bluebonnet Bowl; his notable players at Stanford included quarterbacks Guy Benjamin and Steve Dils, wide receivers James Lofton and Ken Margerum, and running back Darrin Nelson. Walsh was the Pac-8 Coach of the Year in 1977.
In 1979, Walsh was hired as head coach of the San Francisco 49ers. The long-suffering 49ers went 2-14 in 1978, the season before Walsh's arrival and repeated the same dismal record in his first season. Walsh doubted his abilities to turn around such a miserable situation -- but earlier in 1979, Walsh drafted quarterback Joe Montana from Notre Dame in the third round.
Walsh turned over the starting job to Montana in 1980, when the 49ers improved to 6-10. San Francisco won its first championship in 1981, just two years after winning two games.
Under Walsh the 49ers won Super Bowl championships in 1981, 1984 and 1988. Walsh served as 49ers head coach for ten years, and during his tenure he and his coaching staff perfected the style of play known popularly as the West Coast offense.
In addition to drafting Joe Montana, Walsh drafted Ronnie Lott, Charles Haley, and Jerry Rice. His success with the 49ers was rewarded with his election to the Professional Football Hall of Fame in 1993.

1981 championship
Many of his assistant coaches went on to be head coaches, including George Seifert, Mike Holmgren, Mike Shanahan, Ray Rhodes, and Dennis Green. These coaches in turn have their own disciples who have utilized Walsh's West Coast system. Walsh was viewed as a strong advocate for African-American head coaches in the NFL and NCAA. Along with Rhodes and Green, Tyrone Willingham became the head coach at Stanford, then later Notre Dame and Washington. One of Mike Shanahan's assistants, Karl Dorrell has gone on to be the head coach at UCLA. Walsh directly helped propel Dennis Green into the NFL head coaching ranks by offering to take on the head coaching job at Stanford.

Prominent assistant coaches
Several former and current NFL head coaches trace their lineage back to Bill Walsh on his coaching tree:


Bill Walsh coaching tree
After leaving the coaching ranks immediately following his team's victory in Super Bowl XXIII, Walsh went to work as a broadcaster for NBC (teaming with Dick Enberg to form the lead broadcasting team). Walsh returned to Stanford in 1992 to once again serve as head coach for the school, leading the Cardinal to a 10-3 record and a Pac-10 co-championship. Stanford finished the season with an upset victory over Penn State in the Blockbuster Bowl on January 1, 1993 and a # 9 ranking in the final AP Poll. After consecutive losing seasons, Walsh left Stanford in 1994 and retired from coaching.
Walsh would also return to the 49ers, serving as Vice President and General Manager from 1999 to 2001 and was a special consultant to the team for three years afterwards. In 2004, Walsh was appointed as special assistant to the athletic director at Stanford. In 2005, after then-athletic director Ted Leland stepped down to take a position at the University of the Pacific, Walsh was named interim athletic director. He also acted as a consultant for his alma mater San Jose State University in their search for an Athletic Director and Head Football Coach in 2005.
Bill Walsh was also the author of two books, a motivational speaker, and taught classes at the Stanford Graduate School of Business.
Walsh appeared in a recent Coors Light commercial. He plays the role of a coach who answers questions about football. Coors Light-drinking fans ask him questions, saying things such as "We have a 12 pack and four cans" to which Walsh replies "Well, 12 and 4 is pretty good.."
This was actually taking old footage of Walsh's press conferences and editing footage of fans asking questions, and the 12 & 4 comment was probably referring to an opponent's record before a playoff game. Most likely this refers to the Chicago Bears in Walsh's final season of 1988, whom the 49ers handily defeated 28-3 in the NFC Championship at Chicago's Soldier Field in January 1989. The Bears were 12-4 in the regular season and the top seed in the NFC for the playoffs.

Later career
Walsh was diagnosed with leukemia in 2004. In November 2006, he confirmed that he was undergoing treatment for the illness. "News about me has been circulating," he said. "It's been getting back to me. The media has been aware of the possibility of this and has refrained from writing.
"There are too many people following the progress of this. I felt it was appropriate to confirm what's happening. I hope now that I have done that, the media will refrain from phoning me. I'm pragmatically doing everything my physicians recommend and I'm working my way through it," Walsh said.

Personal

Bill Walsh and Glenn Dickey, Building a Champion: On Football and the Making of the 49ers. St Martin's Press, 1990. (ISBN 0-312-04969-2).
Bill Walsh, Brian Billick and James A. Peterson, Finding the Winning Edge. Sports Publishing, 1998. (ISBN 1-571-67172-2).