|Position:||Defensive line coach|
|Date of birth:||November 27, 1952|
|Place of birth:||Warren, Ohio|
|Height:||6 ft 3 in (1.91 m)|
|Weight:||255 lb (116 kg)|
|High school:||Warren (OH) Harding|
|NFL Draft:||1974 / Round: 1 / Pick: 23|
|Career highlights and awards|
|Career NFL statistics|
William Wallace Kollar (born November 27, 1952) is an American football coach and former player who is currently the defensive line coach for the Denver Broncos of the National Football League (NFL). Kollar played as a defensive lineman in the NFL for the Cincinnati Bengals from 1974 to 1976, and the Tampa Bay Buccaneers from 1977 to 1981.
Kollar grew up in Warren, Ohio and attended Warren G. Harding High School, graduating in 1970. He then attended Montana State University, where he was a three-time First Team All-Big Sky Conference selection and a two-time Little All-American. As a junior for the Bobcats, he was named the Big Sky Player of the Year. His jersey #77 has been retired by Montana State.
Kollar has been an NFL assistant coach for 25 years through the 2014 season. He began coaching as a defensive assistant and special teams coach for the Tampa Bay Buccaneers under coach John McKay in 1984. He then spent three seasons at the University of Illinois, first as a graduate assistant and then a defensive line/special teams coach, and two years at Purdue University. He was the defensive line coach for the Atlanta Falcons (1990-2000), St. Louis Rams (2001-2005) and Buffalo Bills (2006-2008) before joining Gary Kubiak's staff in Houston in 2009. He served as the Texans' defensive line coach and assistant head coach from 2009 to 2015. After the 2014 season, Kollar left the Texans and became the Denver Broncos defensive line coach, where he reunited with Gary Kubiak. 
Kollar and his wife, Jan, have two sons, Chad and Clint.
In 1995, Kollar was inducted into his hometown Warren Sports Hall of Fame. On April 10, 2014, he was named to the Senior Bowl Hall of Fame, commemorating the 40th anniversary of his being named MVP of the annual college all-star game.