The Rapper: Kanye West
The Song: "Big Brother," from 2007's Graduation
Who It Was Written For: Jay-Z
Outside of J. Cole's new song for Nas, this might be the most notable example of a rapper writing a song for another rapper. Back in '07, Ye wanted to show Jay just how much he valued their friendship. So he wrote a song about all the good, bad and memorable moments from it. This was bromance at its best.