Sergei


 * You may be looking for Sergei Bazhaev

Sergei was a Russian terrorist working with Oleg Malenov during Cold Warriors.

Cold Warriors
Sergei broke into the security system with Katrina once Randy Bishop had ensured that all personell had been eliminated. When Jack Bauer and his team infiltrated the base, he stayed with the computer to ensure their virus would penetrate the U.S. border and stop all wireless communication. When it dawned on the terrorists that the CTU team was approaching, Katrina and Sergei assumed that they would not have the necessary experience to stop the terrorists' plans, thereby convincing Malenov to leave. They did not anticipate that Chloe O'Brian would be able to stop it.

They tried to escape in a snow cat, but they were pursued by Jack and Amy Seelaki. Jack took out Sergei along with all of Malenov's team.