In no particular order of Greatness:

Dawn of the Dead (1978)

Dawn of the Dead (2004)

Night of the Living Dead (1968)

Night of the Living Dead (1990)

Day of the Dead (1982

The Dead

Zombie

Resident Evil

Resident Evil 3: Extinction

28 Days Later

28 Weeks Later

Zombieland (I hesitate to keep this on the list as it doesn’t exactly fit in zombie horror genre, but it is so good)

Rec

Rec2

Rec3

Rec4

Quarantine

World War Z

and that is all:

I will give honorable mention to: The Beyond, Maze Runner 2, The Girl With All the Gifts, Train to Busan, Return of the Living Dead, The Dead 2, as these are all very enjoyable zombie films, but don’t cut through to be what I consider to be Great.