In the 1932 film adaptation, he was portrayed by the late Leslie Banks.
In the story
When Sanger Rainsford falls off his boat, he ends up at Ship-Trap Island. There he meets General Zaroff, an older man. Zaroff was a Cossack who served in a war under Czar Nicholas II of Russia until his downfall. As a young boy, his father gave him a little gun which was especially made to hunt sparrows.
His father complimented his marksmanship on turkeys, however. He later killed his first bear in Caucasus. However, he later grew bored with hunting, due to the animals that he was hunting weren't as cunning. So eventually, he started to hunt human beings. He fed them well, and made sure that they had lots of exercise.
He also had a training room in his cellar. He offered to have Rainsford accompany him on the hunt, but Rainsford refused. Zaroff then declared that he would be the next to be hunted. If he refused, he would be tortured by Ivan until he agreed.
The hunt begins, with Rainsford getting a head start. Zaroff, Ivan, and his dogs follow close behind. Zaroff taunts Rainsford many times. He comes close to finding his prey hiding in a tree, right above his head. Over the next two days Rainsford is able to build traps that give him the advantage. One of them cripples Zaroff's arms, and the other kills Ivan and the dog. Zaroff corners Rainsford at a cliff edge, but Rainsford jumps off before the general can shoot him.
Zaroff returns home, but cannot enjoy dinner because he is worried over replacing Ivan and Rainsford's fate. He goes up to his bedroom and finds Rainsford there. A surprised Zaroff says that the hunt is over, but Rainsford says that he is now a beast. Zaroff zealously prepares for a man-on-man fight with Rainsford. In the end, it is implied that Rainsford killed Zaroff.
Zaroff is an insane, heartless, and psychopathic man with a thirst to hunt human beings. Despite his psychotic state, he acts like a chivalrous gentleman and is hospitable to Rainsford when he is washed up on the shore.