My main Assault trooper is also call D.O.A and I think it's a fitting nickname for him because his promotion took place right after a mission where he went down and came within a round of dying from bleed out.

I also had a heavy called "Nuke" after he killed 3 cyrssalids and 2 floaters with a rocket. Course he died in a mission soon after :( but oh well can't win them all.