Was a very close friend and mentor to writer/producer/director William Winckler. The two often had three hour luncheons twice a month for many years.
Was encouraged to listen to opera by his father at age 12.
Was reunited with ex-"Lost in Space" (1965) co-star, Bill Mumy, alongside Leonard Nimoy (of "Star Trek" (1966) fame) at a Disney World Convention Center in Orlando, Florida. (1996).
Was very good friends with: Phyllis Diller, Don Adams, Guy Williams, Lorne Greene, John Lasseter, Irwin Allen and Burt Reynolds.
When he wanted to be an actor, he refused to tell his parents about his name change.
When he was attending high school, Jonathan was interested in archeology, Latin, romantic poetry and Shakespeare.
While attending James Monroe High School, he didn't fit in well with his peers, with the exception of his future wife, Gertrude Bregman, who was his best friend.
Would often sit up at night thinking of ways to insult the robot ("Be quiet, you bubble-headed booby!") while on "Lost in Space" (1965). His colorful put-downs for his mechanical colleague, almost all of them unscripted, are among the best-remembered aspects of the show.