Rebuild 1 Edit
Evolved Zombies are more powerful zombies, in game they have only been reported with in zombie horde attacks. This kind of zombie is more intelligent than regular ones. Some of them are larger, faster or stronger than normal zombies.As described by survivors, they are
"Faster, stronger, and bigger than regular zeds."
"F***ing 8-foot tall giants"
or weaker, but able to use a primitive weapon as described in the illustration.
Although it remains unknown throughout the whole game how exactly these zombies have been evolved (mutated), it may be supposed that they have arisen at the big graveyard. No more hordes - and evolved zombies - will appear after the closure of the portal.
Rebuild 2 Edit
Evolved Zombies didn't appear in Rebuild 2.
Super Zombies can use simple weapons, such as a club. They can't attack your fort either, but they can get rid your mission though. Like, Super Zombies are passing the square where you're on mission outside of your base. Beware, because Super Zombies are much harder to defeat than Zombie Mobs, they have more chance to make survivor injury even death.
(+more powerful hordes?,illustration)