I know alot about the movie (Characters and their Description anyway) here's what I know.
Heidi (hippo) - A singer and dancer, she is the big star of the show. She is in a relationship with Bletch. She is severely
bipolar and when upset, she overeacts.
Bletch (walrus) - The boss. He acts as producer for the Feebles troupe, runs porn and drug businesses on the side, and is mean as well. He's in a long-term relationship with Heidi (or possibly married to her, but this is not elaborated on) while in an adulterous relationship with Samantha.
Samantha (cat) - A
prostitute and Bletch's mistress, who gets killed towards the end of the film.
Harry (rabbit) -
Satyristic MC who contracts "the big one", a fatal STD. It is apparently myxomatosis but Harry later finds out it's just "bunny pox."
Trevor (rat) - Bletch's enforcer. Directs pornography and manages the drug business on the side. he also attempts to Rape Lucile
Arthur (worm) - Stage manager. His appearance resembles a book worm. Is an avid cigar smoker.
Sidney (Sid) (elephant) - Animal trainer. A manic depressive who thinks that he has terrible luck. Though he initially denies being Seymour's father, when Seymour is threatened with death in the slaughter which closes the film, Sid acknowledges him and runs to his rescue.
Sandy (chicken) - Has Sid's child out of wedlock. He denies it is his and for this, she is bringing a paternity suit against him.
Seymour (hybrid) - The baby of Sidney and Sandy. He is a half elephant and half chicken hybrid.
Robert (Wobert) (hedgehog) - A new member of the troupe. He has no vices. He falls in love with Lucile. Has a minor speech disorder: He pronounces the letter 'R' as sounding similar to the letter 'W'.
Fly-in-the-sky (fly) - Stereotypical
paparazzo bent on breaking Harry's story. After he publishes it, Bletch and Trevor track him down, rip his wings off and flush him down a toilet.
Sebastian (fox) - The
homosexual stage director with a penchant for sodomy - including an entire song about it. It is presumed he lost an eye during the film's events since the epilogue for the surviving characters shows him with an eye patch.
Wynyard (frog) - Addicted to "every
barbiturate known to man". He is a Vietnam veteran who gets flashbacks about the war and throws knives for the show. He accidentally kills himself during his knife throwing performance.
Lucile (poodle) - Chorus girl who falls in love with Robert after he courts her. At one point, Trevor drugs and attempts to rape her.
Barry (bulldog) - Bletch's driver and enforcer. After raiding the docks with Bletch and Trevor to gain drugs, a large spider bites his head off.
Cedric (wild boar) - A Scottish boar who is part of a large gang, a golfer and tries to double cross Bletch in a drug deal. He is killed when Barry stabs him with a knife.
Louie (dog) - Cedric's side-kick who is a
stereotypical "mangy mutt". He is killed by being force fed borax by Bletch after finding out the drug trade was a scam.
Mr. Big (whale) - Cedric and Louie's boss. Bletch orders Trevor to drive his car through Mr. Big's mouth and they exit out of his "you know what". It presumably kills him.
Madam Bovine (cow) - Heavily pierced and large-uddered cow who stars in Trevor's
porn. She is never seen again after the filming of the porn with Dennis.
"The Masked Masochist" (cockroach) - Actor in Trevor's porn. Dies after Madam Bovine unknowingly sits on his face and suffocates him. Trevor feeds his body to a monstruous whale-like creature.
Dennis (aardvark) After "The Masked Masochist" dies, he is convinced by Trevor to take a part in the porn movie. It looks like semen drips from his nose and he has a penchant for sniffing panties. He dies after sniffing up
borax.
Abi (human) - The only human character, an
Indian snake-charmer and contortionist who physically appears to be a
parody of Gandhi. he gets his body stuck like a ball. when he gets free, a
bed of nails crushes him.
Daisy (dog) - One of the few minor characters of the theater troupe that is given a name. Her name is mentioned by Heidi before the show's debut.
Dr. Quack (duck) - Harry's doctor who told Harry about his illness but later told him the truth when he found out what it really was.
Hope this helps.
and sorry is I used some unusual Vocabulary in the description, I was trying to be specific.