Evolved Zombies are powerful zombies, in game they have only been reported with in zombie hordes. 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.