Matt was born in Washington, D.C. and spent his childhood in Arlington, Virginia, where he was raised by his parents, Frederick W. Clark, a skilled boat builder and cabinet maker, and Theresa (Costello) Clark, the owner and director of a private school in Arlington.
After serving a two-year term in the army, Matt enrolled at George Washington University, but his academic pursuits were cut short when he decided to join a local Washington, D.C. theatre group. This marked the beginning of his journey into the world of acting.
In the mid-1950s, Matt made the move to New York, where he further honed his acting skills at the renowned HB Studio under the guidance of Herbert Berghof and William Hickey.
Matt's early career saw him work at the iconic Living Theater and star in numerous off-Broadway productions. He eventually made the transition to California, where he embarked on a successful film career, appearing in over 50 feature films, as well as countless television movies and TV series.
In addition to his acting credits, Matt also ventured into directing, helming the 1988 film "Da", which starred Bernard Hughes, Martin Sheen, and his former acting teacher, William Hickey.
Matt is the proud father of four children: Matthias Clark, a musician; Jason Clark, a producer; Seth Clark, a film editor; and Aimée Clark, also a producer.