A Survivor Zombie is a player's zombified survivor who has previously died. Now they are zombies and will attack anybody at will.
Survivor Zombies act like common Blighters. They're slow moving and can claw and grab. Each survivor has a name display and their player's overall survival score. Also, they carry backpacks with them which contains all the lost items from the previous player. To acquire them, they must be killed first.
When tracking back to your old survivor after gaining a score over 2250, you may notice that your old self is covered with a reddish smoke that is lingering around them. The better you survived, the harder it gets to kill them when you die.
Be aware that any player can take items from a zombified survivor. In other words, a player may encounter your dead survivor and take your lost items for themselves. Note that this is only possible in the WiiU version.