Vance

First appearance: Digging Up the Marrow (2014)

The Director of Hatchet makes a documentary about monsters after being approached by a man who not only claims monsters are real but that he knows where to find them. Is this man crazy or do monsters actually walk among us?

Nola Carveth's Pyschoplasmic kid

First appearance: The Brood (1979)

Frank Carveth is convinced there's something weird going on at the Somafree Institute. His wife's been there for a while getting treatment for her psychological problems and when his 5 year old daughter came home from her visit she's covered in strange scratches and bruises! What is Hal Raglan's Pyschoplasmic therapy doing to Frank Carveth's wife? Can psychotherapy cause cancer?

One of the early weird David Cronenberg body horror flicks.

Tusken Raider

First appearance: Star Wars (1977)

Along time ago in a galaxy far far away...

A weird mix of Sword and sorcery fantasy and  sci-fi tropes delivers the story of a old religious man convincing a naive farm boy to join a terrorist organization to help destroy a government facility.

The first movie I actually remember seeing in theatres. before all this "Episode 4" and "New Hope" nonsense was attached to it.

Gunther Straker

First appearance: Funhouse (1981)

A group of jerky teens decide to spend the night in a "dark ride" called "The Funhouse." The witness a creepy carny in a Frankenstein mask commit murder after an even creepier interaction he has with another member of the travelling carnival. The teens discover they are locked in the dark ride and after another series of accidentally seeing things that they weren't meant to see and theft, get stalked through the ride by masked carny! Mayhem ensues!
Another sleazy slasher film from the man responsible for The Texas Chainsaw Massacre and Poltergiest, Tobe Hooper.

Jason Voorhees

First Appearance: Friday the 13th Part 2 (1981)

The supposed "Drowned as a child" Jason Voorhees isn't happy that a bunch of camp councillors killed his crazy mom and embarks on an epic quest to rid the world of teens who are into sex, drugs, drinking and dancing to terrible music. After hunting down the girl he saw decapitate his mom he realizes it's probably easier to just hang around in the woods near the campground where he "drowned" and his mom was killed, and wait for victims to just come to him.

Yeah I know Jason doesn't get the hockey mask until the 3d-rd movie but I like him better in the mask.
Interesting bit of trivia, Friday the 13th part 6: Jason Lives is the best reviewed of the series and is widely considered the fan favourite even though it performed the worst at the box office and, unlike any other chapter in the franchise, features no on-screen nudity.

Dr. Peyton Westlake

First appearance: Darkman (1990)
Scientist Dr. Peyton Westlake seeks vengence after being blown up by vicious criminal and amateur finger collector Robert G. Durrant. Unfortunately being blown up has resulted in Dr. Westlake being hideously scarred and losing the ability to feel pain.
Fortunately Dr. Westlake was working on a formula for artificial skin allowing him to make realistic looking masks to disguise himself as anyone. He uses his new found abilities to destroy Durrant's gang and hunt down the man who hired Durrant to blow him up!
This is Sam Raimi's tribute to weird pulpy comic books and the old Universal Monsters.

Ricky Coogin

First appearance: Freaked (a.k.a. Hideous Mutant Freekz, 1993)

On his way to help the E.E.S. (Everything Except Shoes) Corporation promote Zygrot-24, Ricky Coogin and his pal Ernie cross paths with a group of anti-Zygrot-24 protestors lead by the attractive environmentalist, Julie.  Having tricked Julie into believing they are environmentalists too, on their way to protest Zygrot they head into the wilds of Santa Flan, where a side trip to Elija C. Skruggs' Freekland changes their lives. Mutations and mutilations ensue!

The creature designs in this are hilarious. Mr. T plays a Bearded Lady. Keanu Reeves plays a dog!
Not really a movie for everyone, most people probably won't really get the appeal to it. It's weird, juvenile and occasionally a little gross, but with a message: "Even if you don't like macaroons, you should probably eat one if everyone else is doing it."

I actually remember going to see Darkman on its opening night and seeing posters and banners al over the theatre announcing the release of Hideous Mutant Freekz. My friends and I decided to make sure we could get to the theatre to see HMF when it came out. Sadly it never did. A few years went by and I saw a videotape at the local Videoflix called "Freaked" and thought to myself "That looks kinda familiar." Since there weren't any other horror flicks new that week I gave it a shot. Much to my surprise it turned out to be Hideous Mutant Freekz. Turns out the studio was scared about how weird the movie was so they pulled it's theatrical release re-named it and eventually dumped it onto VHS.

Toxic

First appearance: The Toxic Avenger (1984)

The tale of a nerd who is picked on and thrown into toxic waste. This improves his self confidence, so he goes around destroying bad guys and becomes the monster hero of a small New Jersey town called Tromaville. Thus spawning numerous sequels, cartoons, musicals and comic books (one of which I participated in).

Crawford Tillinghast

First appearance: From Beyond (1986)

A pair of scientists, the perverted Dr. Pretorious and his research partner Crawford Tillinghast, build a device known as the "Resonator" hoping to see into other dimensions. Unfortunately it works and Pretorious is killed by the weird creatures now visible thanks to the device. Tillinghast is arrested for the murder and thrown into a mental institution. While under treatment at the mental institution Dr. Katherine McMichaels discovers Tillinghast's pineal glad has been affected by exposure to the "Resonator" and decides he might be suffering from schizophrenia because of this. She decides what would be best for Tillinghast is to go back to the scene of the experiment.
Turns out that even though the creatures ate his head Pretorious is alive, well and just as perverted in the other dimension and he really wants back into our dimension.

I still can't understand how this movie and Re-Animator aired on WUAB-43 out of Cleveland on Saturday afternoons when I was a kid. When it was finally released on DVD a couple years back I picked it up having vague memories of enjoying it as much as Re-Animator. I was right but it really leaves you feeling like you need a shower after watching it.

The Davies' Baby

First appearance: It's Alive (1974)

The heartwarming tale of a hideously deformed, murderous baby and the family who loves him.