 In an interview with The Observer , co @-@ creator Mark Gatiss says that they experienced more difficulty finding the right actor to play Dr John Watson than they had for the title character . Producer Sue Vertue said , " Benedict was the only person we actually saw for [ the part of ] Sherlock ... Once Benedict was there it was really just making sure we got the chemistry for John [ Watson ] — and I think you get it as soon as they come into the room , you can see that they work together " . Several actors auditioned for the part of Watson , and Martin Freeman eventually took the role . Steven Moffat said that Matt Smith was the first to audition unsuccessfully . He was rejected for being too " barmy " , as the producers required someone " straighter " for Watson . Shortly after , Moffat cast Smith as the Eleventh Doctor in Doctor Who . 
