As Roj Blake in the cult series, the Welsh actor led a group of rebels on their Liberator space ship against an evil federation that ruled the galaxy.
Thomas was also an accomplished stage actor who appeared in several Royal Shakespeare Company (RSC) productions.
His later television appearances include playing Nathaniel Clegghorn in ITV’s Heartbeat and David Baddiel’s father in Sky’s Baddiel’s Syndrome.
Born in 1945, Thomas attended the Royal Academy of Dramatic Arts in the 1960s and later became a Rada associate.
His roles at the RSC included Orsino in Twelfth Night, Cassio in Othello and Mat Burke in Eugene O’Neill’s Anna Christie.
Yet he remains best known for Blake’s 7, which ran on BBC One from 1978 to 1981.
At its peak, the series was watched by 10 million viewers and was sold to 40 countries.
Thomas claimed never to have watched a single episode of the show, which was derided by some for its shaky sets and basic special effects.
The show also had a distinctly pessimistic tone – typified by the final episode, in which all the main characters were apparently killed off.
Reports of the actor’s death began to circulate after a Blake’s 7 fan site announced he had died on Wednesday from heart failure.
“Our thoughts are with his wife Linda, and his family and friends,” the message continued.
His death was confirmed by a friend who worked on a Blake’s 7 remake, according to the Press Association.
Fans, friends and former colleagues have been paying their respects on Twitter, among them an actress who said she had appeared with him on stage in Salisbury.
“Our characters hated each other but he was a lovely actor and a lovely man,” tweeted Ruth Mitchell.
Scottish broadcaster Muriel Gray, meanwhile, said she had “adored” Thomas and called the news “miserable”.
Source : BBC