The actor playing role in《Sherlock Season 4》is“Mark Gatiss”

Sherlock's brother, a senior British government official (MI6).His relationship with Sherlock is relatively cold, but in fact he still cares about his smart but rebellious brother. When Sherlock does something outrageous, Mycroft still feels like he hates iron.

He looks strong on the outside, but in reality he is not that strong.