Igor is the assistant and bodyguard to Dr. Boris Balinkoff, an eccentric scientist who lives in a spooky castle on an island close to the Castaways. When Balinkoff brings Gilligan and the Skipper to his home for his mind exchange experiments, Igor serves them dinner then locks them up in the dungeon after finding them wandering around the castle. After succeeding in imprisoning the other castaways, Igor helps Balinkoff in exchanging their minds with each other and then without Balinkoff, exchanging his body with Ginger who in turn uses his brawn and superior strength to help the others escape and regain their true identities. After Igor is returned to normal, he and Balinkoff are trapped in their own Mind-Transference Machine as Gilligan flips the switch, exchanging their minds with a dog and cat in the device. However, this fate may not have remained permanent as Balinkoff returns later as himself, possibly having dismissed Igor for fouling up his long-term plans.
- Igor was played by actor Mike Mazurki, who starred in "It's A Mad, Mad, Mad, Mad World" with Jim Backus and Phil Silvers.
- Igor is not to be confused with the Russian cosmonaut Igor or Balinkoff's pet monkey named Igor.