Sherlock: 10 Most Outrageous Fan Theories

7. Tom Hiddleston Is The Third Holmes Brother

Sherlock fans have been wired about the idea of meeting Holmes Boy No. 3 since his mention in His Last Vow - and only one man could fit the role, according to the internet. None other than Tom Hiddleston.

This is perhaps less of a fan theory and more of a communal wishful thinking but the thought goes that Hiddleston's brother would be named Sherrinford - a character from the wider world of Sherlock Holmes. Although he doesn't appear in Conan Doyle's stories, other writers have created this extra sibling - who is even smarter than his brothers!

The idea has reached co-creator and Mycroft actor Mark Gatiss, who has said that Hiddleston would be amazing on the show and that he would have a word with him about appearing on the series. Fans can influence such things as casting decisions nowadays so, who knows, this one could actually happen.

Even if it's not Hiddleston, it seems likely we'll we seeing the third Holmes brother in Series 4, with 'Sherrinford' one of the tease words the creators offered for the upcoming run.