5 is impossible I also go for a (dirty) dozen

Re-Animator
Night of the Living Dead (original)
Day of the Dead (original)
The Living Dead at Manchester Morgue
Burial Ground
Zombi 2
The House by the Cemetary
City of the Living Dead
Maggie
Dawn of the Dead (original)
Braindead/Dead Alive
The Zombies of Mora Tau

Night
Dawn
Day
Let Sleeping Corpses Lie
Tombs of the Blind Dead

Braindead / Dead-Alive
Day of The Dead (1985)
Zombi 2
Burial Ground
Dawn of The Dead (1978)

This is tough, its my favorite subgenre. If I could only ever watch 6 (honorable mention) zombie movies for the rest of my life..

-Dawn of the Dead (1978)
-Night of the Living Dead (1968)
-The Video Dead (1987)
-Nightmare City (1980)
-Burial Ground (1981)
-Messiah of Evil (1973)

Dawn of the Dead
Night of the Living Dead
Shaun of the Dead
Dead Alive
Return of the Living Dead

Good list.

Have you ever seen I Zombie: Chronicles of pain, Jim? I would like to know what you thnought of it

Not yet. It has been on my to watch list for a while though.

Night of the Living Dead (1968)
Dawn of the Dead (1978)
Day of the Dead (1985)
Dead Alive (1992)
Zombie (1979)

Dawn of the Dead (1978)
Night of the Living Dead (1968)
Day of the Dead (1985)
Return of the Living Dead (1985)
Zombi 2 (aka "Zombie") (1979)

Some others I really like:

City of the Living Dead (1980)
Braindead (1992)
Shaun of the Dead (2004)
Land of the Dead (2005)
White Zombie (1932)
Cemetary Man (1994)
Re-Animator (1985)
FleshEater (1988)

Although it's always been debatable as to whether they're true zombie flicks, I also love the Evil Dead trilogy and 28 Days Later along with 28 Weeks Later.

1. Night
2. White Zombie
3. Day
4. Dawn
5. I Walked with a Zombie
6. Shaun
7. Return
8. Horror Express not “zombie” enough to count.
8. Carnival of Souls
8. The Living Dead at Manchester Morgue
9. Night of the Comet (Borderline zombie movie. I will count it.)
10. Dead Snow

Dawn '78
Night '68
Return of the Living Dead
Dawn remake
Shaun of the Dead