Insane Clown Posse
The rivalry between Detroit's ICP and Eminem has been going on since 1995, beginning with an argument over some flyers Em passed out for a party which said ICP would also be performing.
ICP has made two disses towards Eminem but he countered them with 2 disses on the Marshall Mathers LP in the song Marshall Mathers and on track 12.
Christina Aguilera
This rivalry began when Christina Aguilera had a special on MTV. She volunteered the private info that Em was married to Kim and went on talking about domestic violence and getting out of violent relationships. So em retaliated with a diss in The Real Slim Shady
Cage
After the release of the Slim Shady EP, Cage went around saying Eminem copied his style. They have dissed each other in a number of different rap tunes, including "Role Model" on the Slim Shady LP.
Everlast a.k.a Whitey Ford
Whitey Ford dissed Eminem on record. In return, Em recorded the unreleased "Quitter", mentioning Whitey's heart condition and the poor sales of his LP Eat At Whitey's.
DJ Lethal
A fairly new rivalry, DJ Lethal of Limp Bizkit went on MTV and said that Everlast could kick Em's ass. See about Limp Bizkit for more.
Limp Bizkit
Limp Bizkit is included in the beef that is mainly with DJ Lethal, but affects the whole band. Limp Bizkit was supposed to work on a diss to Whitey Ford with Eminem but backed out at the last minute, this pissed Em off and then DJ Lethal talking shit on MTV was the last straw. "Girls", the diss to Limp Bizkit is a hidden track included on D12's Devil's Night CD.
