Here is the full list of all 43 Over 9000 Zombies! achievements.
Kill 900,000+ Zombies!
Construct 1000 Turrets from random scraps of metal!
Kill 90,000+ Zombies!
Construct 100 automated turrets.
Kill over 1000 crabs!
Kill over 1000 zombie eyes!
Zombie Napoleon meets his zombie Waterloo!
Kill over 1000 zombie crows!
Collect 100 Power Ups!
Kill over 1000 zombie dogs!
No 8th symphony for zombie Sibelius!
Vote for Zombie Thomas Jefferson, or don't.
The zombie world is independent of our will.
Abused patience turns to fury!
Health is the greatest gift, a close second is BRAINS!
Terror possessed me then!
If only he had the body of a horse...
A jail is an isolated system.
Blood and Flesh can be trusted.
Decreased Zombotropy.
Quoth the Raven "Nevermore."
Get 30 kills per second!
Don't call me slow!
Get 15,000 damage per second!
Your world didn't end!
Kill 9,000+ Zombies!
Participate in a multiplayer game.
You didn't donate your organs...
It didn't taste like chocolate ice cream either...
Not a wimp.
Lots of progress!
The army of the undead will march at daybreak!
You watched the world burn, and survived. It was kind of cool.
Green IS good.
Kill 1000+ Zombies!
Voted the greatest zombie of all time!
You won that race.
Making some progress...
Derail the Waltz of the Undead!
Get 10 kills per second!
Get 5,000 damage per second!
The first day is always the hardest, except in this case, it's the easiest.
Construct a turret from scrap metal!