Kapitein Silver serves as the primary antagonist in the 1971 animated film, portrayed as an anthropomorphic pig pirate. He wears a skull-adorned hat and a mustache, with a hook replacing his left hand—a distinct departure from traditional Long John Silver depictions that feature a missing leg instead.

Formerly part of Captain Flint's crew, Silver commands his own pirate ship. His singular goal is to seize Flint’s hidden treasure, motivating his every move. He captures Jim Hawkins and the mouse Gran after they secure Flint’s treasure map, selling them into slavery on Pirate Island before their eventual escape.

Silver’s ruthless ambition drives him to usurp the map from his crewmate Baron, leveraging it for authority before the pirate council. Voyaging to Treasure Island, he repeatedly attempts to steal the map from Flint’s granddaughter Kathy while feigning alliance. His deception includes offering transit in exchange for her guidance, all while plotting betrayal.

A storm destroys Silver’s ship en route. Surviving, he takes Kathy hostage to extract the treasure’s location. He orchestrates a double-cross against his crew and Jim’s group to claim the treasure solely for himself. Forced by Silver, Kathy guides him to trigger a mechanism in the volcanic treasure site. Instead of riches, the mechanism drains the crater lake, sweeping Silver and his monkey helmsman Spider out to sea.

Silver embodies unrelenting villainy and self-interest, lacking the redeeming qualities or paternal ties to Jim seen in other Long John Silver iterations. His leadership relies on intimidation and manipulation, though his crew abandons him upon recognizing his selfish motives.

Silver’s background unfolds solely within the film. After his defeat, he survives and pursues Jim and Kathy on a makeshift log boat, vowing to continue his hunt for the treasure.