Benedict Cumberbatch Sherlock Actor Martin Freeman Watson Actor Una Stubbs Mrs. Hudson Actor Rupert Graves DI Lestrade Actor Mark Gatiss Mycroft Holmes Actor, Writer Andrew Scott Professor Moriarty Actor Natasha O'Keeffe Emilia Ricoletti Actor Jonathan Aris Anderson Guest Star Yasmine Akram Janine Donlevy Guest Star Catherine McCormack Lady Carmichael Guest Star Tim McInnerny Sir Eustace Carmichael Guest Star Paul McGuigan Director Steven Moffat Writer