Smith attended Canoga Park High School, where he was senior class president. He went on to study theater at the College of San Mateo and San Jose State University and earned a drama fellowship from Stanford University's Master of Fine arts program. In the 1970s, he began working regularly with the California Actors Theater in Los Gatos, California. He also attended Santa Clara University. He moved back to Los Angeles to pursue a television and film career. In 1964, he married Cecilia Souza, with whom he had two children. He divorced in 1974. In 1988, he married Joan Pirkle.
Before That '70s Show his other roles included playing Clarence Boddicker, the villain in Paul Verhoeven's influential science fiction action movie RoboCop. He also co-starred as the strict father of Robert Sean Leonard's Neil in 1989's Dead Poets Society. He also made a number of appearances in the Star Trek franchise, playing the President of the Federation in Star Trek VI: The Undiscovered Country, a Cardassian named Thrax in the Star Trek: Deep Space Nine episode "Things Past", and a Krenim scientist named Annorax in the Star Trek: Voyager episode "Year of Hell".
He also has an extensive voice acting résumé, appearing in computer games such as Fallout Tactics: Brotherhood of Steel, and FreeSpace 2, and on a number of animated series. He played a recurring role on the claymation series Gary & Mike as the vengeful Officer Dick and voiced the Dinosaur military commander character General Galapagos in the Savage Steve Holland produced Fox animated series Terrible Thunder Lizards. He currently plays the voice of Bob Johnson on Squirrel Boy.