Between 1974 and 1977, Sam Kelly appeared as Bunny Warren in 11 episodes of Porridge, with Ronnie Barker, and played the same character when the film version of Porridge was released in 1979.
A lengthy run in the TV series 'Allo! 'Allo! began in 1982, with Kelly as Captain Hans Geering.  Geering is Colonel Von Strohm's assistant, and usually accompanies him to Rene's cafe.  Geering is smitten with the waitress Maria, whilst the Colonel prefers Yvette.
IMDb - Sam Kelly
Answers - Captain Hans Geering
BBC Guide - Porridge
Wikipedia - All About 'Allo! 'Allo!
Sam Kelly lists his interests as classical music and cricket.  He has a musical side - not only is he a member of the barbershop group 'The Gay Blades' (with Pinball singer & actor Barry Protheroe), he also sang the role of Sir Joseph Porter in the D'Oyly Carte production of HMS Pinafore in 2002.
Sam Kelly hasn't made many films (he has had brief parts in 2 Carry On films though) but I suppose with all his TV and theatre work, it doesn't leave much time for that!
Another long-running stint came in 1999, with 28 episodes of the ITV sit-com Barbara, where Kelly plays cabbie Ted Liversidge. This followed a BBC 'pilot' in 1995. Ted & Barbara's house, which they used for a lot of the filming, is very close to where I live, and several times I went and watched Gwen Taylor, Sam Kelly and the other actors recording scenes for the programme.
The 1980s saw Kelly in Coronation Street, 12 episodes of Now And Then and a TV version of Charles Dickens' Bleak House.
In the early 1990s, Sam Kelly appeared in 6 episodes of Haggard, at the same time as 19 episodes of On The Up where he played the insolent butler, Sam Jones.
Kelly rejoined the cast for a guest appearance in one episode of Series 7, with Hans now working for British Intelligence! In London, Rene and Edith meet up with Hans who takes them to see Churchill!!  In all, Sam Kelly appeared in 24 episodes of 'Allo! 'Allo!
Sam Kelly left the series in 1987 after the last episode of Series 3, when he is taken by the girls of the Communist Resistance who mistook him for a British airman, and sent him to Britain.
Sam Kelly was born in Manchester in 1943 but grew up in Liverpool.  He joined the Civil Service when he left school, but in 1964 he began a 3 year course at LAMDA (London Academy of Music and Dramatic Arts).
Sam Kelly has an enormous number of TV credits to his name, beginning with The Liver Birds (1972) and The World of Cilla (1973). 
Sam Kelly, Benedict Sandiford & Gwen Taylor in Barbara
Sam Kelly with Ciaran Brown
Cilla Black & Sam Kelly in The World of Cilla
Sam Kelly as Hans Geering in 'Allo! 'Allo!
Sam Kelly & Gorden Kaye in 'Allo! 'Allo!
Sam Kelly as Bunny Warren in Porridge
Sam Kelly as Sir Joseph Porter in HMS Pinafore
Sam Kelly & Guy Siner in 'Allo! 'Allo!
BBC Guide - Haggard
BBC Guide - Now And Then
He signed my book The War Diaries of Rene Artois
I was very pleased to meet Sam Kelly at the Birmingham NEC in August 2007.  I talked to him for quite a while, and I told him that I lived very close to where they filmed Barbara. I asked him if he thought they would do more episodes, but he was sure that there would be no more. 
BBC Guide - On The Up
Sam Kelly & Carmen Silvera in 'Allo! 'Allo!
Sam Kelly as Hans Geering in 'Allo! 'Allo!
Sam Kelly as Hans Geering in 'Allo! 'Allo!
The War Diaries of Rene Artois (autograph page)
Sam Kelly with Cilla Black in The World of Cilla
Sam Kelly as Bunny Warren
in Porridge
Sam Kelly & Gorden Kaye
Sam Kelly & Guy Siner
Sam Kelly & Carmen Silvera
Hans Geering
Hans Geering
Sam Kelly as Sir Joseph Porter
Sam Kelly & Gwen Taylor in Barbara
in HMS Pinafore
Sam Kelly
Click on a name below to take you to that page