The news of his death was confirmed in a statement posted to his Instagram.
It read: "It is with deep sadness that we announce the passing of Dave Courtney at the age of 64... Details about funeral arrangements will be provided in due course.
"His family ask for respect during this period of mourning."
Over the course of his career, Courtney was rumoured to be the inspiration behind Vinnie Jones character Big Chris in Guy Ritchie's gangster movie Lock, Stock and Two Smoking Barrels.
He also worked on the films Six Bend Trap and Clubbing to Death alongside Craig Charles and Nick Moran.
The actor also claimed to be an associate of the Krays and starred in the 1990 film The Krays, starring Martin Kemp.
As well as an actor, Courtney was also an author and published six books, which included Stop the Ride, I Want Off, The Ride's Back On, and Heroes and Villains.
TV director Karl Beattie has paid tribute to Courtney. In a post on X, formerly known as Twitter, he wrote: "Shocked & saddened to hear the tragic news today that Dave Courtney has died.
"A friend for many years, what a great character, always charming, funny and a wicked sense of humour. Whether filming or just hanging out he was a great friend. RIP Dave, peace at last."
A spokesperson for the Metropolitan Police said (as per My London): "Police were called at about 11.25hrs on Sunday, 22 October to a residential address on Chestnut Rise, SE18 following reports of a man found deceased.
"Officers and the London Ambulance Service attended. A 64-year-old man was pronounced dead at the scene.
"His family has been informed. Formal identification has not taken place. The death is currently being treated as unexpected and is under investigation. There have been no arrests."
