(written from a Production point of view)
Karl Bruck (16 March 1906 – 21 August 1987; age 81) was a Hungarian actor who appeared as King Duncan in the Star Trek: The Original Series episode "The Conscience of the King". He filmed his scene on Wednesday 14 September 1966 at Desilu Stage 10.
He is best known for his role as Maestro Ernesto Faustche on the soap opera The Young and the Restless, which he played for ten years from 1977 until his death in 1987.
He appeared in the 1969 film Paint Your Wagon, along with Ray Walston, Harve Presnell, and Robert Easton. Bruck also appeared in the 1971 made-for-television movie The Birdmen, starring Star Trek: Deep Space Nine actor Rene Auberjonois.