Male characters:
Eric Cartman: Has heterochromia, one of his eyes are Brown and one light blue from Kenny McCormick
Kyle Broflovski: Green
Stan Marsh: Blue
Kenny McCormick: Light blue
Tweek Tweak: Blue
Craig Tucker: Gold
Butters Stotch: Sky blue but one eye is pinkish red due to Kenny throwing a ninja star in his eye
Token Black: Dark brown
Jimmy Valmer: Hazel
Clyde Donovan: Blue
Timmy Burch: Light brown
Pip Pirrip: Blue
Damien Thorn: Black
Scott Malkinson: Hazel but mostly green
Dog Poo Petuski: Dark brown
Kevin Stoley: Blue
Gary Harrison: Cyan
Pete (Hair-flip Goth): Brown
Michael (Tall Goth): Brown