Plant-Zombies are Plants with zombie heads.
You may regognize them as your opponents in Zombotany and Zombotany 2.
They also appear in a fan-made game,Plants Vs Zombies 3.
Their leader is Dr. Plantboss,who is Dr.Zomboss' best friend.
“Achievements are a new feature of Plants vs Zombies. Make them here. Note: STOP BEING A TROLL...Your Own Achievements