Slasher is such a hard to define term, and I'm seeing many recomends I wouldn't consider slashers at all (although most I agree fully with). Then again, there is no clear definiton. I'll try to focus my reply on films I consider to either be straight up slashers, or those with many elements of the slash.
The Saw movies for instance, are widely called "torture-porn" (a term I hate and consider misleading). Seeing how it's elaborate traps and killing methods, I just don't feel slasher fits. No one really gets slashed! Many do get tortured, but there's no porn either! I'd call it "torture horror" if anything, and most go too far with the TP thing (that's a joke waiting to happen
). For instance, I've seen Turistas called TP. What? That has slasher elements but is more of a "don't tread from the beaten path" style warning than torture. Who gets tortured? Maybe the one girl who gets slashed, but that's not really torture, it the villian doing his business, nothing more.
Devils Rejects? That's not even horror in my opinion. It is a great movie, but I don't know what to call it besides good old fashioned "f***ed up" (remember when Evil Dead was "that f***ed up movie where a tree rapes a chick"?). "Grindhouse" or "exploitation" would fit it beter than slasher IMHO.
As for some great slashers that would fit the title and haven't been mentioned yet:
The Prowler. Same director as Friday the 13th 4, put a hockey mask on the killer and it's a Friday sequel that's far better than most of the real Friday sequels.
Behind the Mask: The Rise of Leslie Vernon is just a masterpiece IMO. It takes slasher films into a reality no other film has, by watching a guy train to be masked serial killer with hopes of getting his name in with the big boys (Jason, Michael, etc). Almost comedy in many parts, but effective horror secenes as well.
Dolls from Stuart Gordon. They slash!
The Funhouse
The Hazing
Tales From the Hood (some segments, although this blends many horror gernes and is among the most underrated horror films ever.)
Torso
and a couple that are questionable, but I liked.
The Backlot Murders
Cheerleader Camp
Many others I can't think of.
I'm also trying not to include anything with supernatural elements to them, as that slips more into fantasy IMO, even though many of my favs are cross-gernes.
Hope I helped a bit. Also hope I didn't come off wrong and no one thinks I dissed them on their picks or anything. I'm not a certified expert, but have watched enough horror movies in my time that I could be. It's my favorite gerne and makes up at least half of my collection. I even suffer through many DTV disasters in hopes of finding those hidden gems, even more lately as I've re-united with a scholl buddy who now works in managament for the local Borders. He has been filling my player with dozens of screeners for all the new DTV offerings. A couple almost winners from these are Shadow Puppets and Day of the Dead 07. Neitrher are slashers, but they didn't completely suck and entertained me. Avoid The Tomb, the cover is misleading and it has all the quality of a high school film project made by retarded monkeys. I've seen beter acting in porno films.