Let's start by saying how it all started...
"Animaniacs" is a cartoon from Steven Spielberg/Amblin Entertainment, Warner Brothers and Fox Television, the same group that brought you "Tiny Toon Adventures". Many of the people that worked on TTA (Sherri Stoner, Tom Ruegger, Tress MacNeille, etc.) are working on Animaniacs. Animaniacs first aired on Monday, Sept 13th 1993 on Fox in what used to be the TTA time-slot.
The main characters include Chicken Boo, Ralph (Guard), Minerva Mink, Newt (dog), Hello Nurse, Bobby, Squit, Pesto, Marita, Flavio, Mime, Thadius Plotz (CEO), Runt, Rita, Skippy, Pinky, Slappy Squirrel, The Brain, Buttons, Mindy, Dr. Otto Scratchansniff, and Yakko, Wakko, and Dot.
Animaniacs consists of the main show staring the Warner Brothers (Yakko, Wakko, and Dot), along with several mini-cartoons involving the other characters.