Fillers in anime refer to episodes, events, or arcs that do not occur in the original source material, such as the manga. They are created because anime production sometimes outpaces the manga, and they are used to buy time for the source material to create more content. Fillers are usually episodes used by anime, usually between the individual plot points of the major arcs, or between the end of a major arc and the beginning of another one. They can be one-offs or entire arcs of collected episodes, and for new viewers, they can be hard to identify until its too late.

Fillers are often disowned by source readers and disliked in general because they deviate from the source canon, even if they are part of the anime canon. They are called fillers because they rarely move things forward, as they are spliced in and cant change much without disrupting following things from the source canon. Filler episodes do not further the story and usually are of lower quality both visually and narratively. However, some filler episodes might serve the purpose of creating more depth to characters, exploring the interactions between characters, and providing good storytelling, character development, and world-building.

To avoid watching filler episodes, viewers can use Simkls Fillers tab in anime that have one and check the episodes numbers that are marked as a filler. They can also avoid watching anime that uses filler as a means of filling time, especially if they are not watching for enjoyment. If an anime is not intended for the viewer to watch, it will not have filler. However, in order to enjoy a piece of work, viewers must be willing to give it a chance.