Slimer was based off the film version of the character. The ghost's relationship to the team was that of a pet, a mascot, a test subject, and later a full member of the team.
For more information of the movie version of this character go to the movie article.
The Real Ghostbusters The Pilot
Slimer was a sinister ghost who ended up trapped with all the other ghosts. He was also eating a hot dog before he was captured and reached out of the Trap only to get the hot dog in with him.
The Real Ghostbusters
After the Ghostbusters stopped Gozer, they began rebuilding the Firehouse. During this process, the green ghost from the Sedgewick Hotel secretly observed them. Once the Firehouse was fully restored, a celebratory dinner was held. The ghost made himself known and attempted to steal the food. Janine Melnitz speculated Slimer was lonely and the Ghostbusters were the first humans to pay him any attention.
Ray Stantz took a liking and gave him the name "Slimer" just to annoy Peter. When the Ghostbusters were attacked once again by the Spectral Ghostbusters, Slimer bravely volunteered to distract the entities and drain them of their P.K. energy. The Ghostbusters were then able to overpower and trap them. The Ghostbusters agreed to adopt Slimer from then on. However, for official statements from the press and such, Slimer is allowed to freely roam for scientific research conducted by the Ghostbusters.
After the dissolution of the Ghostbusters, Egon elected to stay at the Firehouse and watch over the Containment Unit. Slimer stayed by his side. In 1997, Slimer was frightened by the sudden surge in supernatural activity and flew to Egon's class to tell him the bad news. After the formation of the Extreme Ghostbusters, Slimer was eager to join them in their cases but had to prove himself to the new generation.
- Season 1-2
- Slimer started out the show as a pet. He usually spoke in unintelligible gibberish (although he could piece together simple words, names and phrases at times) and made noises to communicate to the Ghostbusters. Slimer's time was usually spent eating anything he could get his hands on, being a test subject for Egon's experiments, accompanying the team on busts, and accidentally (or intentionally) sliming people. Peter was usually the target of these slimings.
- Season 3-5
- Slimer was changed so he had a tail and could speak in a more understandable manner. Slimer also became more of a regular team member, usually assisting in investigations and busts instead of merely tagging along for the ride.
- Season 6-7
- Slimer was somewhat sort of brought back to a mix of how he was in seasons 1-2. However, he still talks very well.
- Slimer got his own cartoon series in 1988 to reach younger kids. Slimer, along with being able to talk very well, had friends at many places around the local New York Area. Most of the time, he was trying to make money to buy food, helping in get rich schemes, or was dealing with a problem like Manx.
- Extreme Ghostbusters
- Slimer was once again the pet ghost that The Real Ghostbusters had. His appearance was slightly different from the previous series, as he had grown a ghost tail and a slightly bigger face. His face was also less compacted than the previous series. He had apparently stayed on with Egon and Janine. He was acted much like his first version, though a bit less chippy. Slimer was actually much more involved in many ghostly cases than the first series. His voice is noticeably higher in pitch.
Slimer is a harmless, friendly but gluttonous ghost (except in the pilot episode) that wants to help the Ghostbusters. He also loves food, which gets him in trouble early on in the The Real Ghostbusters series. Another notable trait is that he is willing to do whatever he can to help the Ghostbusters. One example was in Slimer, Is That You?, where he has exchanged minds with Egon, but still takes on the Master of Shadows' challenge due to his threat to destroy New York City if Egon does not meet him by the given deadline. Slimer also made selfless sacrifices on Extreme Ghostbusters in the episodes Slimer's Sacrifice, where he let himself get trapped in the storage facility to prevent ghosts from escaping, and Bird of Prey, where he took it upon himself to stop the tornado left by the Harasvelg.
Slimer is a Class 5 Full Roaming Vapor. Egon once cited him as a Full Torso ectoplasmic manifestation, color green, no legs, and spirit classification unknown yet later cited his exact frequency was 500,000 Megahertz.  From then on, Slimer was occasionally referred to as a Class 5. 
Relationship to Others
Slimer and Peter had a love/hate relationship. Unlike the other Ghostbusters, Peter was not as forgiving towards Slimer (mainly because of his initial sliming by the "ugly little spud" at the hotel). However, despite his constant criticisms towards Slimer, Peter began to mellow towards the ghost after Egon's observation that perhaps Slimer's behavioral tendencies are the result of the Class 5 being a ghost that lives with people whose job it is to bust ghosts. While Peter regularly vocalized his intent to get rid of or "blast" Slimer, he was quick to defend him if Slimer was hurt on a job, and would nonchalantly give (or sneak) the green ghost snacks or a pizza. On Extreme Ghostbusters, he appears to have lost all respect he had for Slimer, as he was pretty angry when Slimer took a big bite from Egon's birthday cake.
Egon usually would use him to test gadgets and to study. While Ray may have been the best friends with Slimer, Egon was a very close friend too. Towards the end of the Real Ghostbusters series Egon trusted Slimer with many gadgets.
In Extreme Ghostbusters, Egon and Slimer still remained close and was Slimer's one true friend.
Of all the Ghostbusters, Ray was the kindest to Slimer. He was the first Ghostbuster to treat Slimer with full respect and was even the one that gave him his name (mainly to annoy Peter).
Slimer and Winston sort of had a on off friendship due to Winston's love for the Ecto-1. Winston accepts Slimer's shortcomings and overall gets along well with the spud.
Janine and Slimer had a really strong relationship. Since Janine had to stay up all night waiting for calls and Slimer usually roamed around the place like a dog, the two usually would have nightly activities and snacks together. She did however criticize him at times when his appetite got the better of him, though they still remained friends.
Slimer and Louis were shown to get along together reasonably well.
Stay Puft Marshmallow Man
Most of the time Slimer referred to him as the big guy and would ride on the shoulder of Stay Puft Marshmallow Man. Stay Puft appears to like Slimer a lot, as he stated that he missed Slimer when the green ghost found him in the Containment Unit in "Sticky Business". His fondness for Slimer is made apparent again in "Partners in Slime" when he says hello to him when he sees him.
Like Peter Venkman before him, Eduardo hates Slimer ever since they met face to face at the university. Over time, Eduardo slowly got used to him.
Roland Jackson is not all that much into pets. He seems to not notice Slimer too much.
Garrett Miller and Slimer get along just fine. They both share the same appetite. On some occasions though, Garrett gets mad at Slimer when he eats his food.
Shaky at best. Although neither of the two have a true hatred of each other Slimer is often shown as slightly frightened when Kylie yells (usually at Eduardo).
- In the pilot, Slimer was a bad ghost like in the movie and when the scene where the Ghostbusters captured all the ghosts was used in the original intro, Slimer was replaced by a similar ghost that was blue and had no nose.
- Slimer's ectoplasm, or "slime," can freeze in low temperatures, literally turning him into a ice cube. The experience is not comfortable for Slimer. Oddly, he can eat ice cream, one of his favorite foods, without a problem. Chilly Cooper memorized all his favorite flavors.
- Slimer knows how to read but he moves his lips when doing so.
- In many episodes of The Real Ghostbusters and some episodes of Extreme Ghostbusters, Slimer demonstrated limited shape-shifting abilities. He usually does this as a form of communication.
- During the battle against the Barrow Wights, Slimer displayed the ability to form solid weapons from his slime. He created a baseball bat of solid slime to save his friend and the group of bullies from the creatures. Humorously, Slimer also chased Peter with it for insulting him near the end of the episode.
- It is implied in the episode "Slimer, Is That You?" that Slimer at some extent understands math when the Master of Shadows asks Slimer (who was in Egon's body at the time) to say something, and he responded with "2 times 2 is 4."
- Slimer has slimed another ghost six times: Three times in The Real Ghostbusters (Samhain, Doctor McCatheter, and the Ghostmaster), once in Slimer!(Goolem), and twice in Extreme Ghostbusters(Mirror Demon and Tempus).
- Writers Pamela Hickey and Dennys McCoy pitched a story many times about Slimer coming back to life as a human being. He was to be a 4'11 schlub who wore a suit that didn't fit right and ate a lot. Len Janson liked the premise but the sticking point, oddly, was having to then address Slimer's death. 
- The Kenner "Real Ghostbusters" action figure did not refer to the character as "Slimer", instead calling him "The Green Ghost". His size proportion was much larger to the characters than the Slimer's actual size.
- Slimer also appeared and was given a few lines in the animated anti-drug Cartoon All Stars to the Rescue Saturday morning special.
- Slimer's frequency is 500,00 Megahertz. 
- Shortly after the Gozer incident, Ray gave Slimer his name just to annoy Peter. 
- While in his body, Egon learned that everything tastes like chicken to Slimer. 
- Slimer has to be bribed with food either before or after he's entered or exited the Containment Unit.   
- According to Peter, Slimer's favorite candy bar is Triple Caramel Crunchie. 
- Slimer moves his lips when he reads. 
- At the end of "Poultrygeist," the Ghostbusters find Slimer listening to a new soul music tape. 
- In the May 12, 1988 draft of the episode script, the music Slimer was listening to was from a new James Brown tape. 
- Slimer uses trash from the Firehouse kitchen to make smoothies. 
- In Extreme Ghostbusters, it's shown that Slimer is afraid of (and doesn't like) broccoli.
- In Extreme Ghostbusters, it is unclear why Frank Welker never reprised his role as Slimer, even though he returned to play the part of Ray Stantz (though it is possible that Frank Welker was unavailable in the original casting sessions, and therefore someone else had to play Slimer).
- On page nine of Ghostbusters Issue #1, the costume from "Look Homeward, Ray" is on the bathroom floor of Jim Silver.
- ↑ "Slimer, Come Home"
- ↑ Egon Spengler (2009).The Real Ghostbusters- "Slimer Streak" (1989) (DVD ts. 15:06-15:09). Time Life Entertainment.
- ↑ Pamela Hickey and Dennys McCoy (2009).The Real Ghostbusters- "Halloween II 1/2 " (1987) Visual Commentary (DVD ts. 16:28-17:35). Time Life Entertainment.
- ↑ "Slimer, Come Home"
- ↑ Ray Stantz (2009).The Real Ghostbusters-"Citizen Ghost" (1986) (DVD). (DVD ts. 11:36-11:45). Time Life Entertainment.
- ↑ Egon Spengler (2009).The Real Ghostbusters- "Slimer, Is That You?" (1986) (DVD ts. 16:46-16:51). Time Life Entertainment.
- ↑ "Janine Melnitz, Ghostbuster"
- ↑ "The Revenge of Murray the Mantis"
- ↑ "Sticky Business"
- ↑ Peter Venkman (2009).The Real Ghostbusters- "The Two Faces of Slimer " (1987) (DVD ts. 02:14-02:18). Time Life Entertainment.
- ↑ Peter Venkman (2009).The Real Ghostbusters- "The Grundel" (1987) (DVD ts. 01:38-01:42). Time Life Entertainment.
- ↑ Winston Zeddemore (2009).The Real Ghostbusters- "Poultrygeist" (1988) (DVD ts. 21:27-21:29). Time Life Entertainment.
- ↑ Capizzi, Duane and Roberts, Steven (2009). The Real Ghostbusters Complete Collection Volume Three Disc Five, The Real Ghostbusters- "Poultrygeist" (1988) Episode Script p. 41. CPT Holdings, Inc.
- ↑ Peter Venkman (2009).The Real Ghostbusters- "Ghostworld" (1990) (DVD ts. 07:41-07:43). Time Life Entertainment.