Death Eaters are the followers of Lord Voldemort. The most important death eater, at least during the events of the Order of the Phoenix is probably Bellatrix Lestrange. Other important members include Lucius Malfoy, Augustus Rookwood, Avery, Rodolphus Lestrange, Severus Snape, Barty Crouch Jr, Walden McNair, and Antonin Dolohov.