 Ian McKellenSherlock Holmes | Sherlock Holmes |
 Laura LinneyMrs. Munro | Mrs. Munro |
 Milo ParkerRoger | Roger |
 Hiroyuki SanadaTamiki Umezaki | Tamiki Umezaki |
 Roger AllamDr. Barrie | Dr. Barrie |
 Frances de la TourMadame Schirmer | Madame Schirmer |
 Hattie MorahanAnn Kelmot | Ann Kelmot |
 Phil DavisInspector Gilbert | Inspector Gilbert |
 Patrick KennedyThomas Kelmot | Thomas Kelmot |
 John SessionsMycroft Holmes | Mycroft Holmes |
 Frances BarberMatinee "Madame Schirmer" | Matinee "Madame Schirmer" |
 Charles MaddoxOswald | Oswald |
 Takako AkashiMaya Umezaki | Maya Umezaki |
| ZZak ShukorMasuo Umezaki | Masuo Umezaki |
 Michael CulkinBank Manager | Bank Manager |
| DDavid FoxxeChemist | Chemist |
 Oliver DevotiTicket Agent | Ticket Agent |
| MMike BurnsideAnn's Solicitor | Ann's Solicitor |
 Nicholas RoweMatinee "Sherlock Holmes" | Matinee "Sherlock Holmes" |
| SSam CoulsonMatinee "Thomas Kelmot" | Matinee "Thomas Kelmot" |
 Hermione CorfieldMatinee "Ann Kelmot" | Matinee "Ann Kelmot" |
 Kit ConnorBoy | Boy |
 Zoe RaineyBoy's Mother | Boy's Mother |
 Eileen DaviesLady on Platform | Lady on Platform |
| CColin StarkeyDr. John Watson | Dr. John Watson |
 Sarah CrowdenMrs. Hudson | Mrs. Hudson |
| EElizabeth Jane CassidyWaitress (uncredited) | Waitress (uncredited) |
| JJohn CarrPatron in Cinema (uncredited) | Patron in Cinema (uncredited) |
 Johnny OttoArmy Officer (uncredited) | Army Officer (uncredited) |
 Paul BlackwellStation Passenger | Station Passenger |
