In order of appearance:

Apu - owner of Kwik E Mart

Barney - drunk

Bart Simpsons- needs no introduction

Burns - Homer's boss, owner of the powerplant

Ned Flanders - The Simpsons neighbor, a good Christian

Abraham Simpsons - Homer's father, in retirement

Homer Simpsons - safety inspector, father, husband, son, and overweight

Kent Brockman - news anchor

Lionel Hutz - petty lawyer, then again, all lawyers are petty

Lisa Simpsons - book loving daughter of Homer, too self-conscious

Maggie Simpsons - baby

Marge Simpsons - mother

Milhouse - Bart's best friend

Moe - owner of Moe's Tavern, bartender

Nelson - local bully, soon to be local hoodlum

Ralph - sone of Chief Wiggum, in love with Lisa

Smithers - works in powerplant, Burn's companion

Wiggum - heads the Springfield's police department

Willie - groundskeeper for Springfield Elementary