Victor Drazen is the true primary antagonist of the first season of 24. He is a brilliant terrorist, responsible for genocide campaigns.
Jack Bauer led a team of CTU operatives to kill Victor Drazen, blowing up his compound. However, Victor didn't go in, and survived, although his wife and daughter were killed. Victor was presumed dead, but was imprisoned in an underground prison facility.
Andre and his brother Alexis formulated a plan to release Victor and get their revenge on Jack and David Palmer, who was also involved in the mission. Victor was in contact with Andre and Alexis and was the mastermind of this plan. Eventually, Andre successfully broke Victor out, and they took Jack hostage, but traded him for the severely-wounded Alexis, who died of his injuries shortly after.
The Drazens kidnapped Jack's daughter Kim as leverage over Jack, but when she escaped, they told their mole in CTU, Nina Myers, to tell Jack that Kim was dead, knowing that he would come after them with a vengeance and confident that they could kill him when he did. Jack engaged them in a climactic gunfight at the docks, killing all of Drazen's men and eventually killing Andre as well, before Victor ran out of ammo. After Victor surrendered, a vengeful Jack shot him a total of twelve times, even after Drazen fell dead into the water.