It was 31 years and 4 months.
"Mork and Mindy" ran from 1979 to 1982, with the last original episode broadcast May 27, 1982. Robin Williams did not return to a regular TV series role until September 26, 2013 in "The Crazy Ones" with Sarah Michelle Gellar.
Robin Williams (Mork on Mork and Mindy)
Yes. Mork and Mindy was also a cartoon, where his parents, brother, and sister were introduced.
Jonathan Winters
His car didn't have an Orkan license plate.
Mork and Mindy - 1978 Looney Tunes and Morkie Melodies 2-23 is rated/received certificates of: Argentina:Atp
Mork and Mindy - 1978 Mindy and Mork 3-21 is rated/received certificates of: Argentina:Atp
Mork and Mindy - 1978 Mindy and Mork 3-21 was released on: USA: 7 May 1981
Mork and Mindy - 1978 Mork vs- Mindy 2-6 is rated/received certificates of: Argentina:Atp
Mork and Mindy - 1978 Mork Gets Mindy-itis 2-7 is rated/received certificates of: Argentina:Atp
Mork and Mindy - 1978 Mama Mork Papa Mindy 4-5 was released on: USA: 5 November 1981
Mork and Mindy - 1978 Mork Gets Mindy-itis 2-7 was released on: USA: 21 October 1979
Mork and Mindy - 1978 Mork and Mindy Meet Rick and Ruby 3-17 is rated/received certificates of: Argentina:Atp
Mork and Mindy - 1978 Mork and Mindy Meet Rick and Ruby 3-17 was released on: USA: 26 March 1981
Mork and Mindy - 1978 Mindy Mindy Mindy 3-15 was released on: USA: 26 February 1981
Mork and Mindy - 1978 Rich Mork Poor Mork 4-8 was released on: USA: 26 November 1981
Mork and Mindy - 1978 The Mork Syndrome 2-15 is rated/received certificates of: Argentina:Atp
Mork and Mindy - 1978 Mork's Vacation 2-20 is rated/received certificates of: Argentina:Atp