Here's a list of actors from Downton Abbey that I have seen on stage (Mostly London theatres)
This list is unfinished and may be modified from time to time
If you have your own list let me know and I will post a link here
001 - Robert Crawley, Earl of Grantham - Hugh Bonneville - US and Them — Hampstead Theatre (2003)
002 - Lady Sybil Crawley - Jessica Brown Findlay - Oresteia — Almeida Theatre (2015)
003 - Lady Edith Crawley - Laura Carmichael - Uncle Vanya — Vaudeville Theatre (2012)
004 - Charles Carson - Jim Carter - Fashion — Tricycle Theatre (1990)
005 - John Bates - Brendan Coyle - The Weir — Royal Court (1998)
006 - Baxter - Raquel Cassidy - Sunday Father — Hampstead Theatre (2003)
007 - Lady Mary Crawley - Michelle Dockery - The UN Inspector — Olivier Theatre (2005)
008 - Joseph Molesley - Kevin Doyle - A Midsummer Night's Dream — Barbican Theatre (1995)
009 - Anna Bates - Joanne Froggatt - The Knowledge — Bush Theatre (2011)
010 - Sarah O'Brien - Siobhan Finneran - On the Shore of the Wide World — Cottesloe Theatre (2005)
011 - Lady Rose MacClare - Lily James - The Seagull — Southwark Playhouse (2012)
012 - Tom Branson - Allen Leech - Ecstasy — Hampstead Theatre (2011)
013 - Bertie Pelham - Harry Hadden-Paton - Posh — Royal Court Theatre (2010)
014 - Mrs. Hughes - Phyllis Logan - Gaucho — Hampstead Theatre (1994)
015 - Gwen Dawson - Rose Leslie - Bedlam — Shakespeare's Globe (2010)
016 - Cora Crawley, Countess of Grantham - Elizabeth McGovern - The Misanthrope — Young Vic (1996)
017 - Daisy Mason / Daisy Robinson - Sophie McShera - The Entertainer — Garrick Theatre (2016)
018 - Mrs. Patmore - Lesley Nicol - The York Realist — Donmar Warehouse (2018)
019 - Violet Crawley, Dowager Countess of Grantham - Maggie Smith - Three Tall Women — Wyndhams Theatre (1995)
020 - Ethel Parks - Amy Nuttall - Noises Off — Old Vic (2011)
021 - Alfred Nugent - Matt Milne - Dangerous Corner — Richmond Theatre (2014)
022 - Matthew Crawley - Dan Stevens - The Vortex — Richmond Theatre (2008)
023 - Charles Blake - Julian Ovenden - King Lear — Barbican Theatre (1999)
024 - Dr. Clarkson - David Robb - Half the Picture — Tricycle Theatre (1994)
025 - Isobel Crawley - Penelope Wilton - The Cherry Orchard — Albery Theatre (1996)
026 - Ivy Stuart - Cara Theobold - London Wall — Finborough Theatre (2013)
027 - Duke of Crowborough - Charlie Cox - The Prince of Homburg — Donmar Warehouse (2010)
028 - Sir Anthony Strallan - Robert Bathurst - Alarms & Excursions — Globe/Gielgud Theatre (1998)
029 - Lady Rosamund Painswick - Samantha Bond - Three Tall Women — Wyndhams Theatre (1995)
030 - Stowell - Alun Armstrong - Death of a Salesman — Lyttelton Theatre (1996)
031 - Tim Drewe - Andrew Scarborough - Hamlet — Hackney Empire (1995)
032 - Spratt - Jeremy Swift - Peer Gynt — Olivier Theatre (1990)
033 - Taylor - Lionel Guyett - Julius Caesar — Barbican Theatre (1996)
034 - Judge - Timothy Carlton - Cause Celebre — Old Vic (2011)
035 - Nanny West - Di Botcher - Flesh and Blood — Hampstead Theatre (2000)
036 - Lord Sinderby - James Faulkner - A Patriot for Me — Barbican Theatre (1995)
037 - Nield - Kenneth Bryans - Henry IV part 1 — Barbican Theatre (2001)
038 - Mr. Finch - Martin Walsh - Hobson's Choice — Young Vic (2003)
039 - Lavinia Swire - Zoe Boyle - Six Degrees Of Separation — Old Vic (2010)
040 - Bill Molesley - Bernard Gallagher - Man of the Mode — Royal Court (1994)
041 - Jane Moorsum - Clare Calbraith - Hangover Square — Finborough Theatre (2008)
042 - Man at Smithy - Colin R. Campbell - The Trackers of Oxyrhynchus — Olivier Theatre (1990)
043 - Terence Margadale - Edward Baker-Duly - Rookery Nook — Menier Chocolate Factory (2009)
044 - Sergeant Willis - Howard Ward - Attempts on Her Life — Royal Court Theatre Upstairs (1997)
045 - George Murray - Jonathan Coy - Hedda Gabler — Hampstead Theatre (1988)
046 - Edna Braithwaite (as Myanna Buring) - MyAnna Buring - Strangers on a Train — Gielgud Theatre (2013)
047 - Mr. Dawes - Patrick Brennan - Hamlet — Barbican Theatre (1989)
048 - Green - Nigel Harman - A Chorus of Disapproval — Harold Pinter Theatre (2012)
049 - Mr. Mason - Paul Copley - Prin — Lyric Hammersmith (1989)
050 - Miss Denker - Sue Johnston - The Mysteries - Doomsday — Cottesloe Theatre (1999)
051 - Mabel Lane Fox - Catherine Steadman - Witness for the Prosecution — Concil Room, County Hall (2018)
052 - Lady Shackleton - Harriet Walter - Three Birds Alighting on a Field — Royal Court (1991)
053 - Veteran - Howard Gossington - Nation — Olivier Theatre, National Theatre (2009)
054 - Kiernan Branson - Ruairi Conaghan - Trust — Royal Court Theatre Upstairs (1999)
055 - Kemal Pamuk - Theo James - Sex With Strangers — Hampstead Theatre (2017)
056 - Evelyn Napier - Brendan Patricks - Drawing the Line — Hampstead Theatre (2013)
057 - Larry Grey - Charlie Anson - Richard II — Old Vic (2005)
058 - Count Rostov - Christopher Rozycki - The Editing Process — Royal Court (1994)
059 - Nurse - Elizabeth Hill - The Suicide — Lyttelton Theatre (2016)
060 - Sir Richard Carlisle - Iain Glen - King Lear — Royal Court (1993)
061 - Michael Gregson - Charles Edwards - All My Sons — Cottesloe Theatre (2000)
062 - Mrs. Margie Drewe - Emma Lowndes - Whose Life is it Anyway — Comedy Theatre (2005)
063 - Charles Grigg - Nicky Henson - Much Ado About Nothing — Strand Theatre (1989)
064 - Sir Michael Reresby - Ronald Pickup - The Cherry Orchard — Aldwych Theatre (1989)
065 - Postmistress - Helen Sheals - Through The Mill — Southwark Playhouse (2016)
066 - Reverend Travis - Michael Cochrane - Nuremberg - War Crimes Trial — Tricycle Theatre (1996)
067 - Artificial Limbs Man - Roger Morlidge - Henry V — Barbican Theatre (1997)
068 - Archbishop of York - Michael Culkin - Morphic Resonance — Donmar Warehouse (1999)
069 - Lady Sinderby - Penny Downie - The Merchant of Venice — Barbican Theatre (1994)
070 - White Feather Girl - Gwendolen Chatfield - The Playboy of the Western World — Old Vic (2011)
071 - Amelia Cruikshank - Phoebe Sparrow - Fathers and Sons — Donmar Warehouse (2014)
072 - Mr. McCree - Ron Donachie - Scenes from the Big Picture — Cottesloe Theatre (2003)
073 - Horace Bryant (as Kevin R. McNally) - Kevin McNally - Hidden Laughter — Vaudeville Theatre (1990)
074 - John Drake - Fergus O'Donnell - Macbeth — Greenwich Theatre (1995)
075 - Inspector Vyner - Louis Hilyer - Troilus and Cressida — Barbican Theatre (1996)
076 - Lord Hepworth - Nigel Havers - See U Next Tuesday — Albery Theatre (2003)
077 - Madeleine Allsopp - Poppy Drayton - The Green Bay Tree — Jermyn Street Theatre (2014)
078 - Lord Aysgarth - James Fox - Resurrection Blues — Old Vic Theatre (2006)
079 - Liberal Candidate - Jamie de Courcey - Plenty — Albery Theatre (1999)
080 - Simon Bricker - Richard E. Grant - Otherwise Engaged — Criterion Theatre (2006)
081 - White Feather Girl - Rosie Jones - Berenice — Donmar Warehouse (2012)
082 - Henry Lang - Cal MacAninch - Anna Karenina — Tricycle Theatre (1992)
083 - Sarah Bunting - Daisy Lewis - Three Sisters on Hope Street — Hampstead Theatre (2008)
084 - Jack Ross - Gary Carr - Nation — Olivier Theatre (2009)
085 - Postmaster - Jonathan Jaynes - Saint Joan — Olivier Theatre (2007)
086 - John Harding - Philip Battley - Amadeus — Wilton's Music Hall (2006)
087 - Major Charles Bryant - Daniel Pirrie - The Vortex — Richmond Theatre (2008)
088 - Duchess of Yeovil - Joanna David - Home Chat — Finborough Theatre (2016)
089 - Dent - Karl Haynes - Road — Lyric Hammersmith (2003)
090 - Dr. Ryder - Richard Teverson - A Woman of No Importance — Theatre Royal Haymarket (2003)
091 - Laura Edmunds - Antonia Bernath - Chariots of Fire — Hampstead Theatre (2012)
092 - Prince of Wales - Oliver Dimsdale - The Tempest — The Pit (2000)
093 - Hugh 'Shrimpie' MacClare, Marquess of Flintshire - Peter Egan - Three Hotels — Tricycle Theatre (1993)
094 - Lucy - Hayley Jayne Standing - Dance of Death — Lyric Theatre (2003)
095 - Doctor at Moorfields Hospital - Ian Kelly - A Busy Day — Lyric Theatre (2000)
096 - General Robertson - Jeremy Clyde - Half the Picture — Tricycle Theatre (1994)
097 - Lady Manville - Sarah Crowden - A Midsummer Night's Dream — Barbican Theatre (1989)
098 - Sir John Darnley - Adrian Lukis - Macbeth — Barbican Theatre (1993)
099 - Army Doctor - Graham Padden - Shadowlands — Richmond Theatre (2007)
100 - Hairdresser - Jamie Bradley - A Matter of Life and Death — Olivier Theatre, National Theatre (2007)
101 - Paperboy - Perry Millward - Torch Song Trilogy — Menier Choclate Factory (2012)
102 - Lynch - Andrew Westfield - A Streetcar Named Desire — Lyttelton Theatre (2002)
103 - Princess Irina - Jane Lapotaire - Hamlet — Barbican Theatre (1992)
104 - Major Patrick Gordon - Trevor White - Aunt Dan and Lemon — Royal Court (2009)
105 - Waiter - Tristan Beint - Country Wife — Theatre Royal Haymarket (2007)
106 - Mrs. Drake - Cathy Sara - King Lear — Hackney Empire (1995)
107 - Mrs. Bartlett - Clare Higgins - A Midsummer Night's Dream — Barbican Theatre (1989)
108 - Lieutenant Edward Courtenay - Lachlan Nieboer - Country Magic — Finborough Theatre (2009)
109 - Ethan Slade - Michael Benz - A New World — Shakespeare's Globe (2009)
110 - Susan MacClare, Marchioness of Flintshire - Phoebe Nicholls - Three Sisters — The Queens Theatre (1990)
111 - Mr. Glover - Trevor Cooper - According to Hoyle — Hampstead Theatre (1995)
112 - Lady Anstruther - Anna Chancellor - Stanley — Cottesloe Theatre (1996)
113 - High Sheriff - Gerard Mcdermott - Antony and Cleopatra — Riverside Studios (1995)
114 - Auctioneer - Nicholas Lumley - The Magistrate — Olivier Theatre (2012)
115 - Mead - Edmund Kente - La Grande Magia — Lyttelton Theatre (1995)
116 - Nurse - Issy Van Randwyck - Calico — Duke of York's (2004)
117 - Prosecution Barrister - Nick Sampson - The Relapse (or Virtue in Danger) — Olivier Theatre (2001)
118 - Mrs. Pelham - Patricia Hodge - Heartbreak House — Almeida Theatre (1997)
119 - Doctor - David Acton - King Lear — Young Vic (1997)
120 - Racing Commentator - Peter Hamilton-Dyer - King Lear — Shakespeare's Globe Theatre (2001)
121 - Medical Officer - Richard Hansell - A Patriot for Me — Barbican Theatre (1995)
122 - Tim Grey - Ed Cooper Clarke - The Madness Of George III — Richmond Theatre (2011)
123 - Stall Holder - Joshua Richards - As You Like It — The Pit (2000)
124 - General Sir Herbert Strutt - Julian Wadham - Mountain Language — Lyttelton Theatre (1988)
125 - Neville Chamberlain - Rupert Frazer - The White Devil — Olivier Theatre (1991)
126 - Sir Philip Tapsell - Tim Pigott-Smith - Charles III — Almeida Theatre (2014)
127 - Sir Mark Stiles - James Greene - Una Pooka — Tricycle Theatre (1992)
128 - Mr. Charkham - Mark Penfold - A Long Way From Home — Tricycle Theatre (1991)
129 - Farmer - Nigel Betts - As You Like It — The Old Vic (1989)
130 - Marigold Shore - Sharon Small - The London Cuckolds — Lyttelton Theatre (1998)
131 - Diana Clark - Alice Patten - Hedda — Gate Theatre (2008)
132 - Footman - Richard Dempsey - Dance of Death — Tricycle Theatre (1998)
133 - Registrar - Stephen Omer - No Villain — Old Red Lion Theatre (2015)
134 - King George V - Guy Williams - Rose Rage Part 1 — Theatre Royal Haymarket (2002)
135 - Hotel Porter - Matthew Jure - Talk Radio — Old Red Lion Theatre (2017)
136 - Davis - Stephen Ventura - A Midsummer Night's Dream — Almeida Theatre (1996)
137 - Abbey Visitor - Tom Morley - Five Finger Exercise — The Print Room (2016)
138 - Inspector Stanford - Tony Turner - The Alchemist — Olivier Theatre (1996)
139 - Hospital Doctor - David Sibley - The Positive Hour — Hampstead Theatre (1997)
140 - Hotel Receptionist - Keiran Flynn - Duchess of Malfi — Lyttelton Theatre (2003)
141 - John Ward, MP - Stephen Critchlow - Remains of the Day — Oxford Playhouse (2019)
