Gillian Hanna, who has died at the age of 75 after a long illness, was a protean figure in the alternative theatre movement of the 1970s, co-founding the influential feminist company Monstrous Regiment and, in later years, serving as a mentor to young actors and writers.
An actor of substantial range, she made indelible contributions to productions at the National Theatre, London’s Royal Court, in regional theatres and the West End. She was also an acutely insightful and sensitive translator of plays by Luigi Pirandello, Albert Camus, Dario Fo and other contemporary French and Italian writers.
She was a founding member of Monstrous Regiment. Despite the tongue-in-cheek choice of name (mischievously borrowed from John Knox’s infamous 16th-century tract), Hanna steadfastly refused accusations of militancy.
In a 1987 interview with The Stage marking the company’s 15th anniversary, she explained: “With other groups, politics came first. With us, we’re first and foremost theatrical. But our focus has always been women.”
Born to Irish parents in Buxton, Derbyshire, and raised in Thornton Heath, Surrey, she read modern languages at Trinity College Dublin, where she began acting in student shows. She made her professional debut as Mrs Sullen in George Farquhar’s The Beaux’ Stratagem at the city’s Gate Theatre in 1967.
She was seen as Natasha in Three Sisters at the Liverpool Everyman in 1970 and in CP Taylor’s The Grace Darling Show at the University Theatre (now Northern Stage) in Newcastle the following year. 
Touring with the radical theatre companies 7:84 and Belt and Braces provided her own creative epiphany. Fed up with the paucity and poverty of female roles on offer, she declared: “If I have to play another earth mother/shop steward in orange dungarees, I’ll go mad.”
The experience prompted the formation of Monstrous Regiment, a mixed-gender collective of actors that included Mary McCusker and Chris Bowler, who both became stalwarts of the company alongside Hanna.
Together, they raised the profile of women in theatre and presented new plays from emerging writers who later became key figures, including David Edgar, Caryl Churchill, Bryony Lavery and Michelene Wandor. Hanna’s own translations of European writers gave eloquent voice to the company’s international aspirations.
An early translation for Belt and Braces, of Fo’s Accidental Death of an Anarchist (1979), proved to be her most successful, transferring to the West End and heard in countless regional and touring productions, while her translation of Dacia Maraini’s disturbing Dialogue Between a Prostitute and One of Her Clients (1980) cemented the reputation of the “Monsters” – as they anointed themselves – for provocative topicality.
Her diverse acting choices included a feisty cowgirl in Bryony Lavery’s Calamity (1983) and a deliciously grisly and grotesque Mrs Lovett in Stephen Sondheim’s Sweeney Todd (Half Moon Theatre, 1985). She shared the Globe Theatre stage with Glenda Jackson, Joan Plowright and Patricia Hayes in Federico Garcia Lorca’s The House of Bernarda Alba (1987) and her solo performance of her own translation of Fo and Franca Rame’s triptych of monologues, A Common Woman (1988-89), earned her a Time Out best actress award.
No less remarkable was her raucous and vulgar Martha opposite Russell Dixon’s George at the Sheffield Crucible (1988) in Edward Albee’s Who’s Afraid of Virginia Woolf? – a role far removed from the warmth, generosity of spirit, humour and intelligence for which she was widely known and admired.
The closure of Monstrous Regiment in 1993 saw Hanna blossom elsewhere. A year earlier, she had gained a regional theatre award for Peta Murray’s Wallflowering (West Yorkshire Playhouse) and followed it with a pugnacious account of JB Keane’s Big Maggie (Birmingham Rep, 1993).
A delightfully dipsomaniac Queen Mother in Sue Townsend’s The Queen and I (Vaudeville Theatre, 1994) preceded appearances in Kay Mellor’s A Passionate Woman (Lyric Hammersmith, 1999), Deborah Warner’s revival of Medea with Fiona Shaw (Queen’s Theatre, 2001) and Katie Mitchell’s 2002 staging of Chekhov’s Ivanov at the National Theatre.
Her vivid performance as one of Daniel Radcliffe’s devoted aunts in Martin McDonagh’s The Cripple of Inishmaan  (Noel Coward Theatre, 2013) earned her a WhatsOnStage award nomination and her sole Broadway appearance when it moved to New York.
Hanna’s stage swansong reunited her with Lavery as a sprightly grandma in the writer’s version of Treasure Island at the National Theatre in 2014.
Away from the public eye, her tireless support and advice to writers and actors earned Hanna the affectionate nickname of “the Dame”. A long association with the Royal Court’s writing programmes also saw her mentoring young playwrights and providing translations, most recently Fausto Paravidino’s They Came Into My Field for the venue’s international festival in 2013.
She published a memoir, Monstrous Regiment: A Collective Celebration, in 1991 and remained involved with the company, helping relaunch its website earlier this year.
Gillian Hanna was born on July 20, 1944, and died on August 18. She is survived by her wife Diane Gelon, whom she met in 1980, entered into a civil partnership with in 2005 and married in 2008.