Benedict Cumberbatch Sherlock Actor Martin Freeman Watson Actor Una Stubbs Mrs Hudson Actor Rupert Graves DI Lestrade Actor Mark Gatiss Mycroft Holmes Actor, Executive Producer Louise Brealey Molly Hooper Actor Lars Mikkelsen Charles Augustus Magnussen Guest Star Lindsay Duncan Lady Elizabeth Smallwood Guest Star Andrew Scott Jim Moriarty Guest Star Yasmine Akram Janine Guest Star Wanda Ventham Mrs. Holmes Guest Star Timothy Carlton Mr. Holmes Guest Star Tom Brooke Bill Wiggins Guest Star Louis Moffat young Sherlock Guest Star Steven Moffat Writer, Executive Producer Nick Hurran Director Sue Vertue Producer Beryl Vertue Executive Producer