Oh, and I also thought of The Howling series. Most of the sequels are so bad it can be debated as to which is the worst.

Jason Takes Manhatten was pretty bad. Just too strange to see him out of the woods and stalking the streets. Plus, the kills were all PG 13 looking. Not a true Friday movie at all.

It's interesting. Movies are sometimes like albums - the first one is the best. For instance, in regards to albums, I think the debut record of artists like The Cars, Boston, Alanis Morissette, The Knack, Bad Company and Foreigner were their best. In regards to this forum, the following films seemed to be miles ahead of their sequels.
Saw
Halloween
Hellraiser
Friday the 13th
The Hills Have Eyes
Wrong Turn
Silence of the Lambs
Jeepers Creepers
Hostel
The Exorcist
The Omen
Child's Play

You make a good point. Of those series you listed, what would be your pick for the single worst entry in each?

Diary of the Dead was a mess. It took all the potential in its premise and crapped all over it. I have no urge to see Survival. Also I can't decided which is worse: Jason Takes Manhattan or Jason Goes to Hell. Child's Play 3 was terrible. Don Mancini even owns up to its complete suckage.

With Hatchet III out now, Hatchet is eligible for this listing. I've seen the first two and thought the second was much better.

Can I comment on some that are not listed here?

1. Children of The Corn - I feel the first, 2nd and 3rd were great. After that, all went downhill. But 'Genesis' was extremely unwatchable for me.

2. Creepshow - Creepshow 3 was unwatchable for me. What a waste of time.

3. Return of the Living Dead - While 1 was awesome, 2 is just basically part 1 with different location and added humor, but the rest had gone downhill. I think I remember going wtf at Return of the Living Dead 5: Rave to the Grave.

4. Child's Play - I really dislike Seed of Chucky.

5. Hellraiser - I could only watch the first one, all the rest are weak. But I swear 'Revelations' was totally unwatchable out of all.

6. Poltergeist - 3rd one is the weakest.

7. A Nightmare on Elm Street - Freddy's Dead: The Final Nightmare, most definitely.

8. The Exorcist - The Beginning.

9. Subspecies - Subspecies 4: Bloodstorm is somewhat the weakest.

That's all I can think of at the moment.

No, you can't. Didn't you read the FAQ? It clearly states our stance on these matters. :P

Oh darn.. but I'm a rulebreaker :P

Well I would recommend breaking another rule and watch "Dominion: Prequel to the Exorcist", if you haven't already. It's a little bit like "The Begining", and was actually the first version of the prequel made before the studio took Paul Schrader (the original director and cowriter) off the project and brought in NOES 4 director Renny Harlin in to do reshoots and amp up the blood and lower the psychological elements.

It's not perfect, and has a fair share of detractors of it's own but I definitely think it's one of the biggest unsung heroes of the horror genre. At least the last decade or so.

:)