Kai Leng

Kai Leng was a human assassin and the most trusted agent of the Illusive Man, leader of the human-supremacist organization Cerberus. A former marine of the Systems Alliance with deep anti-alien convictions, he was Earth-born of Chinese and Russian heritage, and his combat prowess and xenophobic nature drew Cerberus to recruit him. Equipped with cybernetic implants and armed with a blade, Leng served as the Illusive Man's chief wet-work operative for over a decade and became one of the principal adversaries of Commander Shepard during the Reaper War. (Mass Effect 3; Mass Effect: Retribution)

Soldier and convict#

Little is recorded of Kai Leng's early life. The Alliance file that Anderson passed to Shepard during the war showed he enlisted in the military in 2172 at the age of sixteen, having faked his credentials. Over the following years he served in patrol and reconnaissance assignments, was reprimanded for taking medals from dead enemy officers, was recommended for a Medal of Valor after a raid, and was accepted into the Interplanetary Combatives Academy, receiving the N7 designation in 2176. (Mass Effect 3)

That same year his career collapsed. While on leave he killed a krogan in a bar fight on the Citadel using a standard service blade, and was dishonorably discharged and sentenced to twenty years in an Alliance prison for first-degree murder. His prowess in combat and his xenophobic nature had by then drawn the attention of the Illusive Man, who arranged for Cerberus to liberate him from prison. (Mass Effect 3)

Cerberus operative#

For more than a decade, Leng served as the Illusive Man's best wet-work operative and assassin. Ruthless, discreet, and methodical, he became Cerberus's most trusted agent, working as an infiltrator and killer. His cybernetic modifications appeared to include the Phantom-class implants used by Cerberus's elite operatives. Among the missions attributed to him before the war, he hunted the rogue agent Paul Grayson, during which he personally killed Liselle, the daughter of Aria T'Loak, and oversaw experiments dosing Grayson with Reaper nanotechnology. He later clashed with David Anderson and Kahlee Sanders during the pursuit of Grayson, and was wounded badly enough that he afterward relied on a cane, though he could still fight much as before. (Mass Effect 3; Mass Effect: Retribution; Mass Effect: Deception)

The hunt for Shepard#

When Cerberus moved against Commander Shepard during the war against the Reapers, Leng was among the forces sent against the Commander. He was equipped with a palm device that projected a kinetic barrier, a projectile weapon built into his gauntlet, a tactical cloak, and a sword for close combat. (Mass Effect 3)

Leng led a Cerberus contingent during the coup against the Citadel Council and came close to assassinating the salarian Councilor; whether that Councilor survived, and whether Leng struck down those who intervened, depended on Shepard's prior choices and on who was present to interfere. He disabled Shepard's skycar in a race to reach the remaining Councilors, ultimately failed his mission, and retreated as C-Sec regrouped, afterward releasing a program into the Citadel mainframe to erase all footage of himself. (Mass Effect 3)

He was later sent to the Temple of Athame on Thessia, where he killed the scientists awaiting Shepard and lay in wait as the Commander discovered a hidden Prothean Beacon and its guardian, a Prothean intelligence that shut down upon detecting Leng's indoctrination. Leng engaged Shepard's team, ordered his gunship to level the temple, and escaped with the data, sending the Commander a taunting message afterward. The trail led to Horizon, where Henry Lawson conducted experiments on refugees at the Sanctuary compound; Leng secured Lawson's research and abandoned the family to the Reaper assault, leaving behind enough information to point Shepard toward Cerberus headquarters. (Mass Effect 3)

Final confrontation#

Shepard tracked Cerberus to Cronos Station, and there Leng revealed himself in the Illusive Man's office, interrupting the Commander. The two fought a final time, Leng summoning waves of Cerberus troopers to his aid. Despite his lethal skill and numbers, he could not overwhelm Shepard, and as his shielding failed he succumbed to the Commander's squad. Gravely wounded, he retrieved his blade and approached Shepard from behind for a killing blow, but the Commander detected and countered the attack, ending the life of Cerberus's greatest assassin. (Mass Effect 3)