Bob Cobb appears in Season Seven. He is introduced to Elaine, who is reluctant to call him Maestro. They hit it off, and become very close. They move to Tuscany at the end of the episode, only to have Kramer and Jerry move there as well.
Bob appears briefly in The Doll, where Elaine reveals they broke up after she spilt a drink on a picture of his favorite tenor (Jose Carrerras). Elaine retrieves a picture they took in Tuscany of a store called Costanza, where a man who resembles Frank sat. He becomes buddies with Kramer and Frank, only to have them break his baton, which he only discovers when he is conducting the orchestra.
Bob is shown to be extremely insecure, and idolizes Leonard Bernstein. He prefers to be called Maestro; he takes extreme exception when people call him otherwise. He also appears to be very specific about neatness, going as far as to remove his pants before a show to prevent creasing.