The actor, who played “Dirty” Den Watts, had been cared for by doctors in hospital in the UK after returning from Bulgaria where he had lived for several years.
Tributes have come in from fellow actors, including Tracy-Ann Oberman who played his second on-screen EastEnders wife Chrissie.
Oberman wrote: “Really sorry to hear about Leslie Grantham. A very very good actor and one who created an iconic character with Dirty Den #RIPLeslieG”.
Best known for his role in the BBC soap, he played Albert Square’s notorious villain Dirty Den from 1985 to 1989.
The 1986 Christmas Day episode – in which Grantham handed over divorce papers to his on-screen wife, Angie – broke all soap episode ratings pulling in over 30 million viewers.
His first stint in the show came to an end in an infamous scene where his character was apparently fatally shot down with a gun concealed in a bunch of daffodils.
A splash was heard, but Den’s death was never actually seen in the final scene.
Fourteen years later, he made a surprise return to Albert Square, revealing he had managed to evade the hitman and flee to Spain with the help of a mistress.
One of the most anticipated TV events of the year, the episode of his return to adopted daughter Sharon’s nightclub attracted over 17 million viewers.
He returned to the screen with the words: “Hello princess”.
A former soldier, Grantham discovered his love of acting while serving a ten-year prison sentence for the murder of a German taxi driver while on army service.
After serving his time in various British prisons, he trained as an actor at the Webber Douglas Academy of Dramatic Art in London.
After playing several small TV parts, including small roles in a 1984 episode of Doctor Who and the mini-series the Jewel In The Crown, he was cast in EastEnders in the role that would make him famous.
Initially reading for the part of Pete Beale, he was offered the part of Den Watts – the landlord of the Queen Vic pub.
Den and his on-screen wife Angie (played by Anita Dobson) soon became two of the soap’s most well-loved characters, and subsequently two of the most recognisable faces on TV.
Away from acting, Grantham co-hosted the physical challenge game show Fort Boyard alongside Melinda Messenger from 1998 – 2001.
In 2004, a Sunday paper published compromising images of the actor – who was married at the time – after he exposed himself during a webcam video chat from his EastEnders dressing room.
In response to what he called “a set-up” he apologised to his friends, family and colleagues and made a donation to charity.
Grantham finally left the show in 2005, coinciding with the soap’s 20th anniversary.
In later years Grantham toured with two stage shows of Jeffrey Archer play Beyond Reasonable Doubt.
The perfect pantomime villain, in later years he received rave reviews for a production of Peter Pan which he directed and starred in, and later he played Ebenezer Scrooge in a theatre production of A Christmas Carol.
Grantham was reported to have completed filming on low-budget Brit flick The Krays: Dead Man Walking just before falling ill.
Grantham leaves behind three children – Spike, Jake and Danny – from his 31 year marriage to former actress Jane Laurie.
A private funeral will be held for friends and family in due course.