Katt was born in South Dakota. He has costarred in many movies and received critical praise for performances in The Limey and SubUrbia. Katt often plays unsympathetic characters, such as an irascible motorhead in Dazed and Confused with Ben Affleck, an ill-fated racist child rapist in A Time to Kill and an embittered business rival in Boiler Room. He was also originally cast to star in the ABC Spring 2006 replacement series The Evidence, but was replaced by Rob Estes. Katt was a child actor as well, appearing as Marc Singer's son on the TV series V. He also was the voice of Atton Rand in Star Wars Knights of the Old Republic II: The Sith Lords.
- The actors William Katt and his father, Bill Williams (birth name Hermann Katt), are his distant cousins.