| Year | Title | Role | Director | Venue |
|---|
| 1964 | A Scent of Flowers | Godrey | | Duke of York's Theatre |
| 1965 | Much Ado About Nothing | Claudio | | National Theatre - The Old Vic |
| Armstrong's Last Goodnight | Protestant Evangelist | | National Theatre - Chichester Festival Theatre |
| Trelawny of the 'Wells' | Capt. de Foenix | |
| 1966 | The Man of Destiny / O'Flaherty V.C. | Corporal Napoleon / Private O'Flaherty | | Mermaid Theatre |
| A Lily in Little India | Alvin Hanker | | Hampstead Theatre |
| Their Very Own and Golden City | Andrew Cobham | | Mermaid Theatre |
| 1967 | The Promise | Leonidik | | Fortune Theatre & Henry Miller's Theatre |
| 1968 | The White Liars / Black Comedy | Tom / Harold Gorringe | | Lyric Theatre |
| 1968–1970 | Richard II | Richard II | | UK tour |
| 1969 | The Bacchae | Pentheus | | Liverpool Playhouse |
| The Prime of Miss Jean Brodie | — | | Director; Liverpool Playhouse |
| Three Months Gone | — | |
| 1969–1970 | Edward II | Edward II | | UK and European tours |
| 1970 | Billy's Last Stand | Darkly | | Royal Court Theatre |
| The Recruiting Officer | Captain Plume | | UK tour |
| Chips with Everything | Corporal Hill | |
| 1971 | Hamlet | Prince Hamlet | | UK and European tours |
| The Swan Song | Svetlovidov | | Crucible Theatre |
| 1972 | The Real Inspector Hound | — | | Director; Phoenix Theatre |
| The Erpingham Camp | — | | Director; Watford Palace Theatre |
| Ruling the Roost / Tis Pity She's a Whore / The Three Arrows | Page-boy / Giovanni / Prince Yoremitsu | | UK tour |
| 1973 | A Private Matter | — | | Director; Vaudeville Theatre |
| 1973–1974 | The Way of the World / The Wood Demon / King Lear | Lady Wishfort's Footman / Kruschov / Edgar | | UK tour; Brooklyn Academy of Music |
| 1974 | Tis Pity She's a Whore | Giovanni | | Wimbledon Theatre |
| Dr Faustus | Dr. Faustus | | Edinburgh Festival & Aldwych Theatre |
| The Marquis of Keith | The Marquis of Keith | | Aldwych Theatre |
| 1975 | King John | King John | |
| The Clandestine Marriage | — | | Director; Savoy Theatre |
| Ashes | Colin | | The Young Vic |
| Too True to Be Good | Aubrey "Popsy" Bagot | | Aldwych Theatre |
| 1976–1977 | Romeo and Juliet | Romeo | Trevor Nunn | Royal Shakespeare Theatre, Aldwych Theatre, Theatre Royal, Newcastle |
| 1976 | The Winter's Tale | King Leontes | John Barton, Barry Kyle, and Trevor Nunn | Royal Shakespeare Theatre |
| 1976–1978 | Macbeth | Macbeth | Trevor Nunn | The Other Place, The Young Vic, & Warehouse |
| 1977–1978 | The Alchemist | Face | Royal Shakespeare Theatre & Aldwych Theatre |
| 1977 | Every Good Boy Deserves Favour | Alexander | Barbican Arts Centre |
| Pillars of the Community | Karsten Bernick | John Barton | Aldwych Theatre |
| The Days of the Commune | Langevin | Howard Davies |
| 1978 | A Miserable and Lonely Death | Kentridge | Walter Donohue |
| 1978–1979 | Twelfth Night / Three Sisters | Sir Toby Belch / Andrei | John Amiel / Trevor Nunn | Also producer; UK tour |
| 1979 | Bent | Max | Robert Chetwyn | Royal Court Theatre & Criterion Theatre |
| 1980–1990 | Acting Shakespeare | Himself | | World tours |
| 1980–1981 | Amadeus | Salieri | Peter Hall | Broadhurst Theatre |
| 1982 | Every Good Boy Deserves Favour | Alexander | Trevor Nunn | Barbican Arts Centre |
| 1983 | Short List | Terry | Mike Ockrent | Hampstead Theatre |
| Cowardice | Boy | Anthony Page | Ambassadors Theatre |
| 1984 | Venice Preserv'd | Pierre | Peter Gill | Royal National Theatre |
| Wild Honey | Michael Platonov | Christopher Morahan |
| Coriolanus | Gaius Marcius Coriolanus | Peter Hall |
| 1985 | The Duchess of Malfi | Bosola | Philip Prowse |
| The Real Inspector Hound / The Critic | Inspector Hound / Mr. Puff | Tom Stoppard / Sheila Hancock |
| The Cherry Orchard | Yermolai Lopakhin | Mike Alfreds |
| 1986–1987 | Wild Honey | Michael Platonov | Christopher Morahan | Virginia Theatre |
| 1988–1989 | Henceforward ... | Jerome | Alan Ayckbourn | Vaudeville Theatre |
| 1989 | Othello | Iago | Trevor Nunn | The Other Place & The Young Vic |
| 1990–1992 | Richard III | Richard III | Richard Eyre | Royal National Theatre & World tour |
| 1992 | Uncle Vanya | Uncle Vanya | Sean Mathias | Royal National Theatre |
| 1993–1997 | A Knight Out | Himself | | UK & US tours |
| 1997–1998 | An Enemy of the People | Dr. Tomas Stockmann | Trevor Nunn | Royal National Theatre & Ahmanson Theatre |
| 1997 | Peter Pan | Mr. Darling/Captain Hook | John Caird | Royal National Theatre |
| 1998 | Present Laughter | Garry Essendine | Malcolm Sutherland | West Yorkshire Playhouse |
| 1999 | The Tempest | Prospero | Jude Kelly |
| 2001–2004 | Dance of Death | Edgar | Sean Mathias | Broadhurst Theatre, Lyric Theatre, & Sydney Arts Festival |
| 2004, 2005 | Aladdin | Widow Twankie | The Old Vic |
| 2006 | The Cut | Max | Michael Grandage | Donmar Warehouse |
| 2007–2008 | King Lear | Lear | Trevor Nunn | Stratford-upon-Avon, Brooklyn Academy of Music, & New London Theatre |
| The Seagull | Sorin |
| 2009–2010 | Waiting for Godot | Estragon | Sean Mathias | Theatre Royal Haymarket, Comedy Theatre, Melbourne, & Fugard Theatre, Cape Town |
| 2011 | The Syndicate | Don Antonio | Chichester Festival Theatre |
| 2013–2014 | Waiting for Godot / No Man's Land | Estragon / Spooner | Cort Theatre |
| 2016 | No Man's Land | Spooner | Wyndham's Theatre |
| 2016–2019 | The Exorcist | Demon (voice) | Birmingham Repertory Theatre & Phoenix Theatre; UK tour |
| 2017 | Shakespeare, Tolkien, Others and You | Himself | Jez Bond | Park Theatre |
| 2017–2018 | King Lear | Lear | Jonathan Munby | Chichester Festival Theatre & Duke of York's Theatre |
| 2019–2020 | Ian McKellen on Stage | Himself | Sean Mathias | UK tour; Harold Pinter Theatre & Hudson Theatre |
| 2021 | Hamlet | Prince Hamlet | Theatre Royal, Windsor |
| The Cherry Orchard | Firs |
| 2022 | Hamlet with Ian McKellen | Performer | Peter Schaufuss | Edinburgh Festival Fringe |
| 2022–2023 | Mother Goose | Mother Goose | Cal McCrystal | Duke of York's Theatre; UK tour |
| 2023 | Frank and Percy | Percy | Sean Mathias | Theatre Royal, Windsor, Theatre Royal, Bath, & The Other Palace |
| 2024 | Player Kings | John Falstaff | Robert Icke | Noël Coward Theatre |
| 2025 | Inside No. 9 Stage/Fright | Guest star (one-night only) | Simon Evans | Wyndham's Theatre |