Was best friends with: Eva Marie Saint, Marlon Brando, Kirk Douglas, Richard Widmark and Carroll Baker.
Was offered a scholarship to attend Chicago's Goodman Theater where he met future wife, Mona Greenberg, a fellow scholarship student. They wed in 1938 and remained married for over 70 years until Karl's death in 2009.
While working at an acting workshop in New York, he brought Eva Marie Saint, whom he knew.