Many of Bill Walsh's assistant coaches went on to be head coaches themselves, including George Seifert, Mike Holmgren, Ray Rhodes, and Dennis Green. After Walsh's retirement from the 49ers, Seifert succeeded him as 49ers head coach, and guided San Francisco to victories in Super Bowl XXIV and Super Bowl XXIX. Holmgren won a Super Bowl with the Green Bay Packers, and made 3 Super Bowl appearances as a head coach: 2 with the Packers, and another with the Seattle Seahawks. These coaches in turn have their own disciples who have used Walsh's West Coast system, such as former Denver Broncos head coach Mike Shanahan and former Houston Texans head coach Gary Kubiak. Mike Shanahan was an offensive coordinator under George Seifert and went on to win Super Bowl XXXII and Super Bowl XXXIII during his time as head coach of the Denver Broncos. Kubiak was first a quarterback coach with the 49ers, and then offensive coordinator for Shanahan with the Broncos. In 2015, he became the Broncos' head coach and led Denver to victory in Super Bowl 50. Dennis Green trained Tony Dungy, who won a Super Bowl with the Indianapolis Colts, and Brian Billick with his brother-in law and linebackers coach Mike Smith. Billick won a Super Bowl as head coach of the Baltimore Ravens.