4. Opie's Sacrifice
Season 5, Episode 3: "Laying Pipe"
In the pilot, Jax convinced his best friend Harry "Opie" Winston (Ryan Hurst) to come back to the club, despite the fact that the latter had spent five years in prison thanks to SAMCRO. When Jax, Opie and Tig end up in prison together, mob boss Damon Pope demands that one of them fight to the death against his men. Opie steps up — and takes a lead pipe to the back of his skull. Many of the show's characters have gone to that great biker hang-out in the sky, but the death of this fan favorite still hurts the most.