Real-life manager of Don Adams.
The characters of Mace and Newfield in Episode #21: "Dear Diary" and Agent Neufeld, mentioned in Episode #123: "Age Before Duty" are named for him.
Mace Neufeld himself appears in a bit part as Herbert, a guest at Max and 99's wedding, in Episode #95: "With Love and Twitches".
He later became a television and film producer.
See Mace Neufeld at Wikipedia.