Born as Tadeusz Zbigniew Danielewski in Radom, Poland, he served in the Polish Underground during World War II but was captured and interred in a German work camp until rescued by Patton's forces. He and his wife, actress Sylvia Daneel (née Sylwia Jadwiga Łakomska; born June 20, 1927), emigrated to the United States in 1948. They formalized their union in the United States with a civil ceremony in Los Angeles, California on June 9, 1950, and shortly after began studying at the University of Iowa. They were naturalized as United States citizens on April 19, 1954 through a Special Act of Congress. The couple later divorced.
After the war, he studied at the Royal Academy of Dramatic Art in London and started the Professional Actors Workshop in New York City, whose students included Martin Sheen, James Earl Jones, and Mercedes Ruehl. He was president of Stratton Productions, Inc. (NYC), a firm engaged in stage, film and TV productions.
He worked at NBC as a studio supervisor and helped develop a new method for directing TV programs. In 1983, he provided the Polish translation of "Sweet Georgia Brown" for Mel Brooks's To Be or Not to Be. He worked at the Brigham Young University Department of Theatre and Cinematic Arts from 1975–89. He moved to head up the USC drama department in Los Angeles until his death in 1993.
Tad Danielewski was married three times.
- First, to actress Sylvia Daneel (née Sylvia Jadwiga Łakomska; born June 20, 1927), who bore him a son, Christopher Danielewski.
- Third, to Lillian Danielewski; that union was childless and ended with Tad Danielewski's death.
- Tad Danielewski IMDb profile; accessed August 11, 2014.
- Tad Danielewski at the University of Wisconsin's Actors Studio audio collection; accessed August 11, 2014
- The New York Times, January 13, 1993
- Article in the Los Angeles Times, January 13, 1993
- Info. regarding Tad Danielewski and Sylvia Daneel (born as Sylwia Jadwiga Łakomska) from the New York City Public Library for the Performing Arts at Lincoln Center (clippings files/3rd floor)
- Sylvia Daneel profile, aticc.org; accessed June 24, 2015.
- Extract with birthdate for Sylvia Daneel, ancestry.com; accessed September 3, 2015.
- Danielewski biodata, The Daily Herald, Provo, Utah, October 16, 1977, p. 23; accessed August 11, 2014.
- "Tad Danielewski, An Acting Teacher And a Director, 71, Dead". The New York Times. January 13, 1993.
- "About Poe". The Official Poe Music Network. Retrieved November 1, 2012.
- "Official Only Revolutions website". Retrieved November 1, 2012.
- "Tad Z. Danielewski; Founder of Actors Workshop". Los Angeles Times. January 13, 1993.