Kai Leng is the main antagonist in Mass Effect: Retribution and Mass Effect: Deception, and the secondary antagonist and final boss in Mass Effect 3. He is a Cerberus assassin and a former N7 operative. Like the vast majority of Cerberus, he is racist towards aliens.
Kai Leng enlisted into the Alliance military in 2172 at the age of sixteen, though his credentials were faked. In 2173, he was reprimanded for stealing medals from fallen enemy officers, but his sentence was reduced due his exemplary service record; he eventually rose to the rank of N7. Leng eventually joined Cerberus after being dishonorably discharged from the Alliance and imprisoned for murdering a krogan at a bar on the Citadel with a standard issue service blade. Cerberus helped him escape prison, and Leng soon became one of the Illusive Man's top operatives.
Mass Effect: Retribution
Kai Leng 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.
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 Prothean VI containing data on the Catalyst from Shepard. Shepard later traces Leng to Sanctuary, a refugee centre on Horizon, which turns out to be a Cerberus facility used to study Reaper indoctrination. The Illusive Man had ordered Leng to Sanctuary in order to retireve the research data from the facility, but by the time Shepard arrives he has already left.
Leng makes his final appearance at Cerberus Headquarters, where he is finally killed by Shepard and the VI is recovered.
- He's supposed to be an evil counterpart to Shepard. Both are former N7 operatives and the best fighters of their respective organizations (the Alliance/Council for Shepard and Cerberus for Leng). However, while Leng hates aliens, the fate of the galaxy hangs on Shepard's ability to rally the other races to fight together against the Reapers. His cybernetic upgrades further parallel them.
- While being primarily Chinese in heritage, he is also of Slavic descent.
- In early concept he was supposed to be a mechanized soldier, later his appearance was designed to look more like an assassin Thane Krios; they even fight once.
- In cut scenes he becomes invisible and summons force field, but not in gameplay despite having the same implants as Cerberus Phantoms.
- He is easily one of the most hated villains in the series, if not the most hated. As a result, the button prompt where Shepard stabs him is widely regarded as one of the most popular in the series.