Katt began his career as a child actor, professionally taking his mother's surname. He adopted the name Nicky at the suggestion of comedian
Harvey Korman. followed by his first film role in
Underground Aces (1981), and further TV roles in episodes of
CHiPs,
Father Murphy, and
V. As an adult, he was known for his role as unorthodox teacher Harry Senate on
David E. Kelley's
Fox drama series
Boston Public. He was often cast as a villain, including as a murderous cop on the take in
Monk, an irascible motorhead in
Dazed and Confused, an ill-fated
white supremacist child
rapist in
A Time to Kill, and an embittered business rival in
Boiler Room. Katt's other roles include Tim in
SubUrbia (1996), Stacy the hitman in
The Limey (1999),
Adolf Hitler in
Full Frontal (2002), Fred Duggar in
Insomnia (2002), Stuka in
Sin City (2005), and Nate Petite in
Snow Angels (2008). He voiced the character
Atton Rand in
Star Wars Knights of the Old Republic II: The Sith Lords. In 2004, he appeared in the
Off-Broadway production of the
Woody Allen play
A Second Hand Memory. Katt's last acting appearance was a 2018 episode of the television series
Casual. In 2020, he participated in a virtual table read with the cast of
Dazed and Confused. ==Personal life==