The Welsh star passed away on Monday morning in a Hertfordshire hospital following a short illness, his agent confirmed.
Born in Merthyr Tydfil, Wales on July 5, 1934, Madoc made his screen debut in the 1961 BBC Sunday-Night Play 'Cross of Iron'.
His notable credits throughout the '60s and '70s included guest stints on The Avengers, Z-Cars and UFO.
He further appeared in 1969 World War II serial Manhunt (1969), starred in a 1971 adaptation of The Last of the Mohicans and played the U Boat Captain in classic Dad's Army episode 'The Deadly Attachment'.
Madoc also made several appearances on Doctor Who, starring in 1968 story 'The Krotons', 1969's 'The War Games', 1976's 'The Brain of Morbius' and 1978/79's 'The Power of Kroll'. He also featured in the 1966 film spinoff Daleks - Invasion Earth 2150 AD with Peter Cushing.
In more recent years, he played the lead role of DCI Noel Bain in police drama A Mind to Kill (1994-2002).
Madoc's final acting credit was in last year's fantasy short Hawk from Welsh writer / director MJ McMahon.
Watch a clip of Philip Madoc in Dad's Army below: