He was best known for being a cast member on the ABC soap opera All My Children and was the first American to play the role of Henry Higgins in the Broadway production of My Fair Lady.

He was drafted while he was a graduate student in music at Indiana University Bloomington and spent his time in the United States Army performing in shows for troops stationed in South Korea.

[2] In the 1961 Broadway production of My Fair Lady, Keith served as an understudy to Michael Allinson and played the role of Higgins some 50 times.

[2] In 1992, Keith was one of the founders of TACT (The Actors Company Theatre), which has the mission of presenting "neglected or rarely produced plays of literary merit", appearing in its productions of Eccentricities of a Nightingale and Bedroom Farce.

[2][3] Keith also appeared on Broadway in Titanic in 1997 in the role of Macy's owner Isidor Straus who sang the song Still to his wife Ida as the boat was sinking into the ocean.