William Conrad, star of the television series "Jake and the Fatman," "Cannon" and other shows, died of a heart attack on Friday at the Medical Center of North Hollywood. He was 73.

A hospital spokeswoman, Tricia Spellman, said that Mr. Conrad had become ill at home and died soon after being taken to the hospital.

The corpulent Mr. Conrad was the second half of the title on the CBS Television series "Jake and the Fatman," playing J. L. McCabe, a tough district attorney and former cop. The series ran from 1987 to 1992. He also starred in the detective series "Cannon," which ran from 1971 to 1976, and for eight months in 1981 he played the reclusive, orchid-growing detective Nero Wolfe on NBC.

His voice was probably as well known as his figure, for he was the narrator of several popular television series, including "Buck Rogers" in 1950 and the Bullw

inkle segments of "The Bullwinkle Show" in 1961. Before James Arness put on his spurs, Mr. Conrad was the radio voice of Marshal Matt Dillon in "Gunsmoke" on CBS (1952 to 1961), and from 1963 to 1967 he kept television viewers informed of the weekly activities of Richard Kimball on "The Fugitive." From 1973 to 1978 he narrated the documentary "The Wild, Wild World of Animals," and in 1977 he did double duty, serving as narrator of the suspense anthology "Tales of the Unexpected." Produced and Directed

He had other talents as well. In 1963 he was brought in as director of the failing television series "77 Sunset Strip," and kept it going through 1964. He produced several feature films, including "Chamber of Horrors" (1966), "An American Dream" (1967) and "Countdown" (1968), and both produced and directed "Two on a Guillotine" (1964) and "Brainstorm" (1965).

His acting roles ranged from "The Killers" (1946), "Arch of Triumph" (1948), "Cry Danger" (1951) and "Johnny Concho" (1956) to a television appearance in "The Mikado" in 1982.

Mr. Conrad was born on Sept. 27, 1920, in Louisville, Ky., where his father owned a theater. The family later moved to California.

He is survived by his wife, Tippy, and a son, Christopher, of Seattle.

William Conrad (1920)