If you are searching for the "worst of the worst", or "best of the best gore", depending on your preferences, you will find information regarding some trend setting and appalling films here.  

Why did I bother with this page?  Because gore and controversy are frequent topics in the horror community.  However, it is very difficult to determine what these films are actually comprised of since the hype is often misleading.  

The looseness of the events in many of these make it hard to care what happens from one scene to the next.  This is the kind of information that gets lost in the hype of these movies.  Yes, they are truly disgusting and gory.  

But do they offer something more?  

Below is the list and the FrightFiles.net YouTube video 

featuring the picks for the 15 most disturbing films of 

all time.  

Cutting Moments:

It is very rare that a film sticks with you like this one will.  I saw it years ago and remember everything about it.  While films like the August Undergrounds and Cannibal Holocaust are talked about more frequently, Cutting Moments may be the most brutal.  I am not sure that there is another film on the planet that compares.  With a running time of less than 30 minutes, this film tells a better story than most full length features.  Cutting Moments is one story in a film with 5 shorts.  The others are considerably more tame.  In my opinion, the Cutting Moments short is a masterpiece.  However, I only recommend it if you are comfortable with unflinching brutality in horror.

The August Underground Series:
August Underground
August Underground's Mordum
August Underground's Penance
WARNING-  I would read the reviews around the web before viewing any of the AU series!
Having seen all three of these, I can honestly say that these are absolutely some of the most disturbing movies ever produced.  These films get worse (or better depending on your perspective) with each new release, with Penance being brave enough to tackle some things that are generally off limits, even in horror.  If you want excessive gore, you will certainly find it here!  I personally liked the third installment (Penance) the best in this series.  They are all shocking, but the story and production of the third appealed to me more.  Fred Vogel is earning his way into horror history.  I give him credit just for having the courage to produce these. 
 All of the ToeTag movies offer some very well done gore.  Not generally listed in the disturbing category, but a phenomenal movie, is The Redsin Tower.  
Cannibal Holocaust:
I am sure most everyone is aware of this one.  It is certainly a gore filled film, including the now infamous impaled woman scene.  One word of warning- There is a significant amount of graphic animal cruelty in this film.
Planet Terror:
Perhaps the most fun I have ever had watching a horror film!  Great gore and tons of it!!  Add to the gore a fun story and entertaining cast, and you have one of my all time favorites.
Blood Feast:
Keep in mind that this one was filmed in 1963.  Although influential and probably way ahead of its' time, I have never been a fan of HG Lewis because the gore is simply not well done.  Assuming that you have seen some of Lewis' work, his idea of what appears to be mangled body parts is simply poorly done.  Even given the time frame, just not very impressive. 
Slaughtered Vomit Dolls:
Blood and vomit anyone?  Not a great film, but certainly worth a mention for the gore effects which were undoubtedly good.

A great film.  This movie reminds me of the old days when directors actually tried to scare people rather than just make a gross out movie.  Scary and brutal.  

Dead Alive (AKA Braindead which was actually the original title):
A classic horror comedy from Peter Jackson.  Yes, this is Peter "The Lovely Bones, King Kong, Lord of the Rings" etc., etc., Jackson.  He really did some wicked gore back in the day.  Dead Alive is one of the goriest movies ever and quite funny as well.  Check out the Jackson directed "Bad Taste" as well.