- If you were looking for the butler of Platinum in Pokémon Adventures, see Sebastian (Adventures).
Sebastian is a character of the day who appeared in The Treasure Is All Mine!, as James's butler. He did not receive a name in the Japanese version.
Sebastian was shown to have a fondness for James and was also worried about his future. After meeting James unexpectedly in the mansion, he tried to catch him and make him marry Jessebelle, in accordance to James's parents' wishes.
After initially failing, Sebastian contacted Jessebelle prematurely and informed her that James was in the mansion. He then assisted her in trying to capture and marry him. Though they were successful, James eventually managed to escape from the mansion, but unintentionally brought Jessebelle with him.
- As is the case with James's other butlers, Hopkins and Mr. Cheeves, Sebastian was unnamed in the Japanese version but ended up being named in the English dub.
- Juan, Selphy, and Platinum also have butlers named Sebastian.
- Sebastian shares the same Japanese voice actor as Hopkins, another of James's butlers, and Growlie, James's first Pokémon.