She appears to have Pink Hair in a Ponytail and has a bang lapping over her head. Same blue eyes as her Good counterpart, but has more eyelashes and pink eye shadow. She also wears a purple dress with a belt along with purple leggings and sleeves with holes along with gold beads each arm. Evil Princess appears to have a different sort of crown and wears jewelry, which her good twin does not wear normally.
She's supposed be the opposite of the Princess, albeit, she's not too helpful.
Being the opposite of Princess What's-Her-Name, she's not as strong and very sensitive. She is also vain, as she keeps applying makeup to assure that she still looks beautiful, hates having her hair messed up and breaking her nails when firing her own gun. Aside from her problems, she still does her best to be in Evil Jim's team.
Evil Princess, strangely, loves to go on a dates, which she mentioned to Earthworm Jim, despite that Princess What's-Her-Name does not know what a date is or what is love either.
In one scene, as Evil Princess was putting on makeup before going to fight Earthworm Jim's team, Evil Princess kisses Evil Jim, In doing so, she shows that she admires him, unlike her good counterpart. And, unlike his own twin, Evil Jim doesn't know Evil Princess' love for him and is oblivious to her advances.