Laps' Skeledog adds a new undead companion to Minecraft, appropriately named the Skeledog!
Found deep within the Nether, this hostile creature can be defeated, resurrected, and eventually tamed into an incredibly powerful companion.
Adds the Skeledog
To begin resurrecting a Skeledog, combine its head with:
Resurrected Skeledog Head:

Once the head has been infused with life, place it on the ground and feed it bones. After it has been fed enough, the resurrection will be complete and your new companion will be tamed!
I hope you all have fun with your powerful new undead companion!
They are loyal, dangerous, and surprisingly good at taking on some of Minecraft's strongest enemies.
P.S.
100 Skeledogs versus 100 Wardens is pretty entertaining.