Billie Whitelaw, who has died aged 82, was one of the great "new wave" working class actors of the 1960s, hailing from the provinces (born in Coventry, raised in Bradford) like her game-changing contemporaries Albert Finney, Robert Stephens and Joan Plowright.

Beautiful, blonde and fearsomely direct, she offered a rare combination of a finely tuned intellect and natural voluptuousness, first in Laurence Olivier's National Theatre company at the Old Vic (where she shared a dressing room with Geraldine McEwan and Maggie Smith) and then in a series of new plays in the 1970s by David Mercer, Michael Frayn and Samuel Beckett, the latter coming to think of her as his muse after she gave the British premiere of Not I – the chattering monologue of an isolated gob in a black void – at the Royal Court in 1973.

She had been ill for the last few years of her life, living in the actors' home, Denville Hall, but had become a close friend and mentor of Lisa Dwan, the Irish actress whose own Not I, following Whitelaw's tuition and a study of Beckett's notes to her, returns to London next year as part of the Barbican's international Beckett season.

She last appeared on the London stage in Edward Albee's Who's Afraid of Virginia Woolf? at the Young Vic in 1987, playing opposite Patrick Stewart (Saskia Reeves and Matthew Marsh were the young couple) but described in her autobiography – Billie Whitelaw…Who He? – how she lost her nerve and her ambition. She never appeared on the stage again, apart from her solo Beckett turns.

Earlier in that same decade she had given unforgettable performances in the RSC's ten-play tragedy cycle, The Greeks, in the original cast of Peter Nichols's Passion Play, also at the RSC, and as the drunken, vulgar wife of novelist Heinrich Mann in Christopher Hampton's glorious fable of the European screenwriters' emigrant enclave in Hollywood during the war, Tales from Hollywood, at the National in 1983, when she made a sensational entrance with a candlelit birthday cake wearing only a very small white pinafore.

Her films included Hitchcock's last, Frenzy, in 1972, The Omen four years later, and as mother of the sibling gangsters in the Philip Ridley-scripted The Krays in 1990. Best of all were her two early low budget movies with Albert Finney, quondam lover and lifelong friend, Charlie Bubbles (1967) and Gumshoe (1970). She was first married to the actor Peter Vaughan and secondly to the writer and critic Robert Muller, who died in 1998.