(written from a Production point of view)
John Abbott (5 June 1905 – 24 May 1996; age 90), born John Albert Chamberlain Kefford, was an English actor who worked steadily from the thirties to the eighties, amassing dozens of television guest appearances, and movie roles – almost a hundred and fifty total. He was particularly active in sixties television, with guest appearances in many of the shows of that era. He played Ayelborne in the Star Trek: The Original Series first season episode "Errand of Mercy".
Abbott filmed his scenes on Thursday 26 January 1967 at Desilu Stage 9, Friday 27 January 1967 at the "Arab Village" section of the 40 Acres backlot, Monday 30 January 1967, Tuesday 31 January 1967 at Stage 9, and Thursday 2 February 1967 at Stage 10.
Nine months after filming "Errand of Mercy", Abbott coincidentally uttered (at 13:50) that TOS episode title to Vince Howard in the Bewitched episode "Samantha's Da Vinci Dilemma".
He lent a quiet dignity to the roles he played, even in relatively weak plots like Lost in Space. According to William Blackburn, Abbott was a very professional, Shakespeare-trained classic actor. (TOS-R Season 1 HD DVD Special Features)