The British Independent Film Award for Best Supporting Actor is a discontinued annual award given by the British Independent Film Awards (BIFA) to recognize the best supporting performance by an actor in a British independent film.
Since 2008, two categories named Best Supporting Actor and Best Supporting Actress are presented.
Actors Eddie Marsan and Sean Harris are the most nominated actors in this category since its creation in 2008 with three nominations each.
In July 2022, it was announced that the performance categories would be replaced with gender-neutral categories, with both Best Supporting Actor and Best Supporting Actress merging into the Best Lead Performance category.
Additionally, a category named Best Joint Lead Performance was created for "two (or exceptionally three) performances that are the joint focus of the film, especially where performances share a large number of scenes and screen time".