Andrew Scott who plays Moriarty gives him a dangerous and phycotic air, with chilling coal black eyes.
Moriarty is mentioned in the first two episodes of the first series, showing he has links to other worldwide criminals.
The first time he appears, posing as Molly's boyfriend, he fools Sherlock into believing he's gay, and dismisses him.
He sets Sherlock a number of tests, strapping bombs to people in the street and giving Sherlock a time limit. The last victim he takes is John, who is the first hostage to cause Sherlock alarm.
He originally plans on killing Sherlock and John, then changes his mind and wonders off to kill somebody else. Later in the episode he is seen recieving a text from Irene Addler.
In the last episode of the series Moriarty gets himself arrested, then threatens the jury to get off. He then begins to convince the world that Sherlock is a fake, by pretending to be an actor that Sherlock hired, selling his story to the press.
When he and Sherlock meet on the roof of the hospital, he tells Sherlock to jump or he'll have John, Lestrade and Mrs Hudson shot. He then claims that Sherlock is boring, until Sherlock shows him that he and Moriarty are the same, even if Sherlock is "one the side of the angels" he is not one of them.
Moriarty then shoots himself, leaving Sherlock's only option to jump.
At the beginning of the episode Moriarty was captured and tortured by Mycroft's men, while here, he manages to extract stories of Sherlock's early life from Mycroft that he then uses against Sherlock.
- He is insane and less subtle than the usual Moriartys
- Moriarty is portrayed as slightly camp
- He does not go over the building with Sherlock, but shoots himself insted.