Jay Z & Dame Dash
Cause: Ah, Jay and Dame, Dame and Jay. What was once the most powerful duo in hip-hop suffered an ugly split around 2006 when Jay become the CEO and President of Def Jam. Their baby, Roc-A-Fella records, was sold to Def Jam (which Jay now ran) and a now ousted Dame started his own label, the Dame Dash Music Group. While there seem to be a million different reasons for the split, many simply blame it on a souring relationship between the two former BFFs. Hov was apparently becoming fed up with Dame's lust for celebrity and Dame wasn't stepping down.
Currently: How are Hov and Dame now? Funny that you ask. Recently the two have seemingly reconciled. After an Instagram video of Dame enjoying Jay's Magna Carta... Holy Grail surfaced, the two were seen kicking it at an industry party. The other bi-products of their beef, most notably the Cam'ron and Jay fued, are also no longer much of an issue.