1. Big Smoke and Ryder
It turns out that the Grove Street family bond isn't for life. The Johnson family's long time allies Big Smoke and Ryder betrayed the gang to have their own taste of power. They thought that they were too good for the gang life, so they sold their gang out. While it might take a long time to see them again, CJ gets to exact his revenge.
The interesting thing is that Big Smoke and Carl even talk before the former dies and end things on a civil note.