Cassian

Cassian is the tertiary antagonist of John Wick: Chapter 2. He is the bodyguard of Gianna D'Antonio and an old colleague of John Wick.

He was portrayed by the rapper, Common.

History
Cassian sighted John Wick as he was going to assassinate Gianna and briefly exchanged words with him.

After John kills Gianna, Cassian pursues him and engages in a brutal fight with him. However, their fight is interrupted when they crash into the Rome Continental, and are told by Julius to stop fighting and go have a drink at the bar.

While at the bar, the two discuss their motivations, and John Wick tells Cassian that he killed Gianna because Santino D'Antonio forced him to with the Marker he gave him. Cassian expresses understanding of why John did what he did, but also states that he has a duty to get revenge on John.

Later, while John is being pursued by an army of assassins, Cassian also goes to confront him. The two engage in a fight that ends up leading to a knife duel on a subway train. The fight ends when John stabs him in the chest, incapacitating him, and leaves him on board the subway train.