Alfred Ryder (born Alfred Jacob Corn; January 5, 1916 - April 16, 1995) was an American film, radio and television actor, best known for appearing in over one hundred television shows, including the starring role as a British criminal who could not be killed in Alcoa Presents: One Step Beyond episode "The Devil's Laughter'" (1959). He appeared in the landmark first-aired episode (but not the first episode filmed in production order) of Star Trek on September 8, 1966. In "The Man Trap," Ryder played Prof. Robert Crater, who is hiding the fact that the creature pretending to be the professor's wife, Nancy - as well as who appears to Dr. Leonard McCoy to be the same woman, but his long-past love who seemingly hasn't aged a day - is actually a shape-shifting, sodium-craving, murderous monster who will do anything to get salt. But, as Crater explains, it is also the last of its kind.
Ryder played the main alien leader, Mr. Nexus, in the 1967-68 (two seasons) TV series The Invaders. He also appeared as the ghost of a World War I German U-boat captain in two episodes of the 1960s Irwin Allen-produced ABC-TV series Voyage to the Bottom of the Sea. He later appeared in an episode on another Irwin Allen-produced series on ABC, as a cantankerous orphanage operator, Parteg, in the February 1969 episode "Night of Thrombeldinbar," on Land of the Giants.
He began acting at the age of eight and went on to study with Robert Lewis and Lee Strasberg. He eventually became a life member of The Actors Studio. Born to Jewish parents, he was married to actress Kim Stanley from 1958 until 1964; the couple had a child, Laurie Ryder. He was the brother of actress Olive Deering (1918–1986).