The Older Brother Spider Demon was a member of the Spider Family.

The older brother Spider Demon body takes the form of a giant spider possessing a human head, his face similar to the Mother and Older sister demon has the same facial features of red dots and pure white skin and white hair similar to his "younger brother" Rui with the only difference being that his eyes possess dark red almost pitch black Sclera with deep blue iris's and pupils.

The Older Brother Spider demon is shown to be sadistic and cruel, that in the flashbacks of the Mother Spider Demon he openly taunts and enjoys the physical and verbal abuse she was being put through by Rui and the Spider Demon Father,while sarcastically calling them "Mother" and "Father", showing that he sadistically enjoys playing the part of being in a "Family".

(Source: Kimetsu no Yaiba Fandom)