Kollar played as a defensive tackle in the National Football League (NFL) for the Cincinnati Bengals from 1974 to 1976, and the Tampa Bay Buccaneers from 1977 to 1981.

[1] 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.

He spent more than a decade (1990-2000) coaching the defensive line for the Falcons, highlighted by an NFC Championship in 1998 and an appearance in Super Bowl XXXIII against Denver.

During his tenure with the Texans, the team ranked eighth in the NFL in total defense (329 .4 ypg) and third in the league in opponent third-down percentage (35.9).

[8] Defensive ends Mario Williams, Antonio Smith and J. J. Watt combined for five Pro Bowls playing for Kollar in Houston.