- Served in the U.S. Navy during World War II.
- Acted opposite his father, Jason Robards Sr., only once, in the 1959 play The Disenchanted.
- Preferred the stage to film work, and didn't act in films until he was 37.
- His big break was in the 1956 off-Broadway play The Iceman Cometh, playing salesman Hickey. He reprised the role in the 1960 TV movie and again in the 1985 Broadway production.