This is about as close to pure evil as I’ve seen:

Destructive behavior has mostly been investigated by games in which all players have the option to simultaneously destroy (burn) their partners’ money. In the destructor game, players are randomly paired and assigned the roles of destructor versus passive player. The destructor player chooses to destroy or not to destroy a share of his passive partner’s earnings. The passive partner cannot retaliate. In addition, a random event (nature) destroys a percentage of some passive subject’s earnings. From the destructor player’s view, destruction is benefit-less, costless, hidden and unilateral. Unilateral destruction diminishes with respect to bilateral destruction studies, but it does not vanish: 15% of the subjects choose to destroy. This result suggests that, at least for some, destruction is intrinsically pleasurable. (more)

Mind you, its not an especially large evil. But it is an unusually pure evil. And 15% of lab subjects do it!