Frank Kelly (born 1938) is an Irish actor whose career has spanned radio, TV, theatre, music, writing and films. An educated and learned man, he has played a wide variety of roles in Irish theatre over many years, and he has toured extensively in the U.S. and Canada. Despite his varied career, he is perhaps best known for playing Father Jack Hackett (an old and somewhat perverse priest who usually only says "drink!" "arse!" "feck!" and "girls!") in the hit comedy series Father Ted aired originally in the United Kingdom in April 1995 and ran through until May 1998.

He was brought up in a middle-class Dublin household; his father was the editor of the "Irish Punch", the famous Dublin Opinion. He claims his desire to become an actor began when he saw a cartoon in which a clown on a stage looked sadly at things being thrown at him. "It seemed to me like a kind of Calvary, kind of triumph over adversity by perseverance and smiling on."

Frank starred in popular RTÉ children's programme Wanderly Wagon alongside Eugene Lambert and Nora O'Mahoney from 1968-1982, playing a number of different characters and writing many of the scripts.

His work on Hall's Pictorial Weekly established Kelly as one of Ireland's most recognisable faces, and led to him winning a Jacob's Award in 1974.

He has been married to Baibre Neldon since 1964, and they have seven children. His first ever role in film or television was as an uncredited prisoner in the classic film The Italian Job (1969), opposite Noel Coward as 'Mr Bridger'. He appeared in the film Rat in 2000, and also in the short film, Yu Ming Is Ainm Dom, in 2003. For his role in Father Ted, he is said to have worn contact lenses (to show Father Jack's blank eye), and he said that people wouldn't talk to him if he was in his Father Jack make-up.

He appeared in the film Taffin in 1982.

He released a single, Christmas Countdown, which reached number 8 in the Irish Singles Chart in 1982 and peaked at 26 in the UK Singles Charts, a full twelve months later in 1983, and an album, Comedy Countdown, which featured a sketch taken from his radio show, The Glen Abbey Show. The show which was on RTÉ during the 1970s came on at 2.30 pm each weekday. Many of his popular sketches started with the sound of him putting coins in an old phone coin box, and when the phone rang and was answered, his words were, "Hello! Guess who?"

He is currently doing the voice-over for the Post Office advert on television.

His work for various Irish charities, although unpublicised, has been formidable.

On 6th February 2008 it was confirmed that Kelly has been suffering from Bowel Cancer. Having had his tumor removed in September 2007 he is now undergoing a course of chemotherapy in order to lower the risk of the disease returning.

"I had cancer of the bowel. It was the size of a bloody cabbage."

Kelly also confirmed that he is expected to make a full recovery from the disease and that no secondary cancers were found during routine tests. His course of chemotherapy is due to be completed in April 2008.

Professor Frank Kelly, FRS (born 28 December 1950) is professor of the Mathematics of Systems in the Statistical Laboratory of the University of Cambridge, and Master of Christ's College, Cambridge.

His research interests are in random processes, networks and optimisation, especially in very large-scale systems such as telecommunication or transportation networks. In the 1980s, he worked with colleagues in Cambridge and at British Telecom's Research Labs on Dynamic Alternative Routing in telephone networks, which was implemented in BT's main digital telephone network. He has also worked on the economic theory of pricing to congestion control and fair resource allocation in the internet. From 2003 to 2006 he served as Chief Scientific Advisor to the United Kingdom Department for Transport.

He was elected a Fellow of the Royal Society in 1989. In December 2006 he was elected 37th Master of Christ's College, Cambridge in succession to Malcolm Bowie.

Scored a UK Top 30 hit in December 1983 when the humourous 'Christmas Countdown' (a spoof of The Twelve Days of Christmas) reached 26 in the UK singles chart. He later received a letter from the Queen explaining how the record had given her "great pleasure".

He has a Bachelor of Law from University College Dublin and despite being called to the Bar he has never practiced law in Ireland.