Sheldon J. Plankton/Appearances

For appearances in seasons 1-8 of the main series, go to Sheldon J. Plankton/Appearances (Seasons 1-8)
For appearances in seasons 9-13 of the main series, go to Sheldon J. Plankton/Appearances (Seasons 9-13)
For appearances in all seasons of the main series since season 14, go to Sheldon J. Plankton/Appearances (Season 14-Present)
For appearances on Kamp Koral: SpongeBob's Under Years, go to Sheldon J. Plankton/Appearances (Kamp Koral: SpongeBob's Under Years)
For appearances on The Patrick Star Show, go to Sheldon J. Plankton/Appearances (The Patrick Star Show)
For appearances in feature-length movies, go to Sheldon J. Plankton/Appearances (Feature-Length Movies)
For appearances in shorts and specials, go to Sheldon J. Plankton/Appearances (Shorts and Specials)
For appearances in books, go to Sheldon J. Plankton/Appearances (Books)
For appearances in video games and phone apps, go to Sheldon J. Plankton/Appearances (Interactive Media)
For other appearances in the SpongeBob franchise, go to Sheldon J. Plankton/Appearances (Other)

Here are a few rules:

Nicktoons crossovers are counted.
Bold means Plankton was the main character of and/or played a major role in a specific episode, movie, short, book or video game.
Italic means Plankton appears in a feature-length movie, a book, a video game, or a musical. It is also used for the titles of television shows that he appears in.
Episodes where Plankton cameos, appears in a deleted scene, appears as a entirely different character not related to him or appears in a time card, as well as episodes where only his voice is heard, count as episode appearances. However, episodes where he is a entirely different character related to him (e.g. PlankBot in Welcome to Binary Bottom) do not count.
All episodes are listed by production order unless an episode has only one segment broadcast at the moment (for the main series and Kamp Koral: SpongeBob's Under Years as of now). Upcoming episodes with available screenshots are acceptable.