British comedy icon Terry Jones has died at 77, as reported by his agent to the BBC. A founding member of British comedy troupe Monty Python since 1969, Jones was also celebrated for his work as a screenwriter, film director, poet, historian and author.

Jones’ agent confirmed his passing was due to dementia that had plagued the comedian for at least three years and left him unable to speak, after his son Bill publicly explained his suffering in September 2016. The statement revealed that he was “with his wife Anna Soderstrom by his side after a long, extremely brave but always good humoured battle with a rare form of dementia, FTD,” and affirmed that “We have all lost a kind, funny, warm, creative and truly loving man whose uncompromising individuality, relentless intellect and extraordinary humour has given pleasure to countless millions across six decades.”

The comedian was long lauded for his portrayal of middle-aged mothers in the troupe, channeling a high-pitched voice for the bit. Jones’ directorial debut, Monty Python and The Holy Grail, is highly regarded as one of the best pieces of British comedy, grossing more than any British film exhibited in the U.S. the year of its release. Jones additionally found success as a historian and children’s author, having written several books and presented television documentaries about the medieval time period.

Jones is survived by widow Soderstrom and daughter, Siri, who was born in 2009, as well as his two children from his first marriage, Bill and Sally.