Spider fighting or spider derby is a sport involving spiders that occurs in different forms in several areas of the world. Among them are the Philippines, Japan, Singapore and Malaysia. The fights that occur in the Philippines and in Japan are staged between females of various species of web weavers. Female spiders will kill a rival if the loser does not quickly flee or receive the aid of a human handler. The contests that are staged in Malaysia and Singapore are fights between male jumping spiders. The males fight only for dominance, and ordinarily the loser will flee, though sometimes they will lose a leg in the fight.

A blood sport or bloodsport is a category of sport or entertainment that involves bloodshed. Common examples of the former include combat sports such as cockfighting and dog fighting, and some forms of hunting and fishing. Activities characterized as blood sports, but involving only human participants, include the ancient Roman gladiatorial games.