Kai Leng

Kai Leng is one of the main villains in Mass Effect: Retribution and Mass Effect: Deception, and the tertiary villain and final boss in Mass Effect 3. He is a Cerberus assassin and a former N7 operative. He is racist towards aliens.

He joined Cerberus after being discharged from the Alliance and imprisoned for murdering a krogan at a bar. Cerberus helped him escape prison. After Mass Effect 2, Leng became one of the Illusive Man's top operatives.

In Retribution, he is sent to capture a former member of Cerberus called Paul Grayson and later to murder him when Reaper tech indoctrinated him and made him too dangerous to live. In Deception, he is tasked with retrieving Paul Grayson's body from the Citadel.

In Mass Effect 3, he is amongst the Cerberus forces attacking the Citadel during the the attempted coup. He encounters Commander Shepard whilst attempting to assassinate the salarian councillor. He also appears later on Thessia where he takes the data on the Catalyst from Shepard.

At the end of the Alliance assault on Cerberus' headquarters, Kai Leng is killed by Shepard and the data is recovered.