Sergei Petrenko

Sergei Petrenko was a Ukrainian national and the head of a criminal organization in Los Angeles, California.

Petrenko was involved in the manufacture of methamphetamine at a cabin in the Santa Monica Mountains, working with a female chemist with whom he was infatuated. The woman, unknown to him, was actually an undercover special agent with the FBI, Sue Mishler.

Petrenko's group arranged the sale of a large amount of methamphetamine to Felix Studhalter, a local drug distributor. Smiley Lopez, head of Petrenko's rival gang MS-13, agreed to give up what he knew about Zapata to Jack Bauer if Bauer agreed to steal the meth shipment for him. Tony Almeida and Nina Myers arrested the real Studhalter in Los Feliz so that Jack could go undercover as Studhalter and acquire the drugs for Lopez.

Jack arrived at Petrenko's safe house in Santa Monica at 1:10pm, where Petrenko's relative Malenkiy searched him. Petrenko explained that, under the terms of the deal, the three of them would drive to the meth lab in the Santa Monica Mountains, where Jack would get the drugs and a clean truck to transport them. After they left in Petrenko's Mercedes, Jack was directed to an apartment complex where another man, Franko, joined them. The four took Pacific Coast Highway to Topanga Canyon, eventually arriving at the cabin outside Topanga. Unknown to Jack, corrupt CTU agent Peter Jiminez had intentionally released Studhalter from custody, allowing him to contact Petrenko on his satellite phone just before the deal concluded and ruining Jack's cover. Petrenko ordered Malenkiy to kill Jack and drop his body off the nearby cliff, then departed in the Mercedes, with Franko following behind in the meth truck.

With Agent Mishler's help, Jack overpowered Malenkiy and took off down Topanga Canyon in pursuit of the mobsters. Petrenko opened fire on their vehicle, but Agent Mishler returned fire, managing to strike and kill Petrenko and forcing his car off the road.