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Richard Allen Dysart (March 30, 1929 – April 5, 2015) was an American actor. He is best known for his role as senior partner Leland McKenzie in the television series L.A. Law (1986–1994), for which he won a 1992 Primetime Emmy Award as Outstanding Supporting Actor in a Drama Series after four consecutive nominations. In film, he held supporting roles in The Hospital (1971), Being There (1979), The Thing (1982), Mask (1985), Pale Rider (1985) and Wall Street (1987).
Description above from the Wikipedia article Richard Dysart, licensed under CC-BY-SA, full list of contributors on Wikipedia.
Filmography
Hard Rain (1998)
as Henry Sears
Back to the Future Part III (1990)
as Barbwire Salesman
Pale Rider (1985)
as Coy LaHood
The Thing (1982)
as Dr. Copper