Nehemiah Persoff

Deaths in Film:

Men in War (1957) [Sfc. Nate Lewis]: Killed in an explosion when he panics and runs after walking into a minefield.

The Comancheros (1961) [Graile]: Stabbed in the back by Iphigenie Castiglioni; he dies shortly afterwards while talking to his daughter (Ina Balin). (Thanks to Brian)

The Power (1968) [Professor Carl Melnicker]: Dies of a heart attack (offscreen) caused by Michael Rennie's telekinetic power. George Hamilton and Suzanne Pleshette find his body sitting in a chair.

Psychic Killer (1975) [Dr. Gubner]: Killed (off-screen, exact method unclear) by Jim Hutton's astral form; his body is seen when Julie Adams discovers it in Jim's bedroom.

Alfred Hitchcock Presents: Heart of Gold (1957) [Ralph Collins]: Stabbed in the stomach by Darryl Hickman in self-defence during a struggle in the kitchen.

Playhouse 90: The Killers of Mussolini (1959) [Benito Mussolini]: Executed, along with Ilka Windish, by a firing squad of partisans; their bodies are then hanged upside-down.

The Twilight Zone: Judgment Night (1959) [Carl Lanser]: Dies (off-screen) under unspecified circumstances, some time before the episode begins; he wakes up on board a British ship, and eventually discovers that his own U-boat sank the ship and that he is being forced to relive the sinking over and over again.
Rawhide: Incident of White Eyes (1963) [Domingo]: Presumably killed by Apache Warriors after being hole up in a stagecoach weigh station. With Eric Fleming, Diana Millay and Nita Talbot as the only other survivors Nehemiah makes a run for it to save their lives knowing it was he the Apaches were after for breaking their tribal taboo. We last see Nehemiah riding over a hill with the warriors in close pursuit.

The Wild Wild West: The Night of the Inferno (1965) [General Andreas Cassinello]: Shot to death (off-screen) by Victor Buono's men after they take him away; we only hear the shot as Victor talks to Robert Conrad.

Voyage to the Bottom of the Sea: Deadly Creature Below (1966) [Dobbs] Drowns (offscreen) after escaping from the submarine.

The Wild Wild West : The Night of the Underground Terror (1968) [Major Hazard] Shot in a gunfight with Robert Conrad.

Columbo: Now You See Him (1976) [Jesse Jerome]: Shot to death by Jack Cassidy.
Greatest Heroes of the Bible: Daniel and the Lion's Den (1978) [Malamar]: Eaten off-screen along with Dean Stockwell and either Andrew Bloch or Harvey Solin (unclear which one) by lions.

St. Helens (1981 TV) [Mr. Ellison]: Killed during the eruption of Mount St. Helens.

Murder, She Wrote: The Great Twain Robbery (1990) [Constantin Stavros]: Shot to death (off-screen) by Roy Dotrice. His body is shown afterwards (covered by a sheet) on a stretcher and a layout on the floor of Nehemiah's study.