Alexei Stukov is one of the commanders of the Expeditionary Fleet sent by the United Earth Directorate to the Koprulu Sector and the secondary antagonist of the StarCraft expansion Brood War.
After being infested and de-infested by the Zerg, Stukov would later resurface as a major character in StarCraft II.
After the United Earth Directorate discovered the existence of the Zerg and Protoss, Stukov was assigned to lead a UED Expeditionary Fleet alongside his old friend Admiral Gerard DuGalle to the Koprulu Sector with the goal of bringing the Terrans there under UED control and to eliminate both the Zerg and the Protoss before they could reach Earth.
Unlike DuGalle, Stukov had less reservations with employing the Zerg as part of their campaign and with the order they were given to seize the second Zerg Overmind so the Zerg could be controlled by the UED through it.
The Expeditionary Fleet, under Stukov and DuGalle's command, had many early victories against the Terran Dominion. They later allied with a group of Confederate Resistance Forces led by Samir Duran that were also opposing the Dominion. Stukov was suspicious of Duran, especially after Duran convinced DuGalle to destroy a Psi Disruptor they had discovered on Tarsonis. In the effort to seize the device, Stukov secretly had the device dismantled and then reassembled at Braxis behind DuGalle and Duran's backs.
Upon DuGalle's discovery that Stukov had defied his orders, he sent Duran and his forces to execute Stukov for treason. However, as his position was overrun, Stukov informed DuGalle that Duran was actually infested by the Zerg, right before being killed by Duran. Stukov's personal forces then joined up with the rest of the UED fleet in fighting off Duran's forces and securing the Disruptor. Thanks to Stukov's actions, the UED were given a massive advantage in their campaign against the Zerg, though ultimately it was not enough to stop them from being defeated by the alliance of the Zerg, Protoss and Terrans.
Stukov's body was later seized by the Zerg and reanimated as an infested Terran. Stukov served as the commander of a Zerg Brood, until he was captured by Raynor's Raiders and cured of his infestation with a nanite serum developed by the Protoss. Stukov was later given to the Moebius Foundation so they could research the cure he was given, only to instead be imprisoned by the Foundation's head, Dr. Emil Narud, and experimented on. While there, Stukov discovered that the Foundation was secretly experimenting to create Protoss-Zerg Hybrids
Stukov later escaped and joined the Zerg Swarm led by Sarah Kerrigan. Stukov informed Kerrigan of the Hybrid experiments the Terran Dominion was doing and assisted her in her campaign against the Terran Dominion.
After the three races allied once more and invaded the void to kill Amon once and for all, Stukov was one of the zerg leaders participating in the fight against Duran/Narud, revealed to be a Xel'naga lieutenant of Amon's. After they reached him, Stukov finally achieved his long-awaited revenge and personally slew him with a corrosive bolt, as any Xel'naga who dies in the void dies permanently. Stukov even mirrored Duran's quote before he killed him, "Say goodnight."