Ira Kenneth Reiner (born February 15, 1936) is an American lawyer.
He was the Los Angeles City Controller from 1977 to 1981, and was the Los Angeles City Attorney from 1981 to 1984, both times being succeeded by James Hahn. He was the Los Angeles County District Attorney from 1984 to 1992. As District Attorney he supervised the prosecution of several notorious cases, including the murder trial of Richard Ramírez, the widely publicized police arrest of Rodney King, and the McMartin preschool trial, the best known case of day care sex abuse hysteria.
In 1990 Reiner was an unsuccessful candidate for the Democratic nomination for California Attorney General, losing to Arlo Smith, who in turn was defeated by Republican Dan Lungren. In 1992 Reiner sought re-election as District Attorney, but trailed Gil Garcetti in the June non-partisan primary. Initially Reiner stayed in the race, but in September he dropped out.
After retirement from office he entered private practice with the firm of Riley and Reiner.