
Acting
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.

Everything Is Terrible! The Movie
as Self (archive footage)

Proteus: A Nineteenth Century Vision
as The Ancient Mariner (voice)

L.A. Law: The Movie
as Leland McKenzie

Hard Rain
as Henry Sears

Todd McFarlane's Spawn 2
as Cogliostro
Corwin
as Self

Panther
as J. Edgar Hoover

Truman
as Henry L. Stimson

A Child Is Missing
as Riley Hallihan

Marilyn & Bobby: Her Final Affair
as J. Edgar Hoover

Spawn
as Nicholas Cogliostro (voice) · 18 ep.

E! True Hollywood Story
1 ep.

Batman: The Animated Series
as Dr. Bartholomew (voice) · 2 ep.

L.A. Law
as Leland McKenzie · 171 ep.

Blood & Orchids
as Harvey Koster · 2 ep.

The Andros Targets
as Dr. Kipness · 1 ep.

Gemini Man
as Leonard Driscoll · 1 ep.

Baretta
1 ep.

Doctors' Hospital
1 ep.
Doc
1 ep.
Pale Rider
1985