The Avengers : Season 1

"The Frighteners," "Girl on the Trapeze" and the first twenty minutes of "Hot Snow" are the known episodes to exist of the first season. All the other episodes of season one were destroyed by the BBC in a bulk wipe, to which many classic shows have been lost [IE: Dr. Who, Dad's Army, The Spies, etc.) We do hope that the rest will pop up someday, somewhere, somehow...