Earthworm Kim is a major character in Earthworm Jim 3D. She embodies Jim's long-suppressed feminine side, intent on taking on Jim's mind and body. Jim had to defeat her and save his masculinity. Kim also becomes a playable character after the game is beaten and all of the marbles have been found. Playing as Kim doesn't affect the game much aside from changing the game difficulty to hard and changing the final boss to Earthworm Jim.
Earthworm Kim wears a Super Suit just like Jim, but it is purple and has bracelets on the gloves. Kim's head sports a large blonde wig, large eyelashes, a purple bow, and small pink diamond earrings. Her irises are also purple.
Although it predates her first appearance in Earthworm Jim 3D, there was a brief scene in the intro of the animated series where Jim had a wig on. In that brief scene, he resembled Kim, except his wig was brown instead of blonde and he had no makeup on.
- While talking to Jim, she says that she wants to use his credit cards, a possible spoof of the TV joke that teenage girls borrow their parents' credit cards to buy stuff.
- The pig she's riding on in the final battle is similar to Jim's pig, but is darker, has a darker red nose, red hooves, red pupils, and fangs. The only normal thing noticeable about the pig is that its stomach is pink.
- Her real name is Earthworm Kim, as she is called that in-game when you unlock her after completing the game 100% as Jim. She is, however, still referred to as a male because of the rushed development.
- If you get to where Earthworm Kim would be when you are playing as her, she will be replaced by Earthworm Jim, but the dialogue between them is unchanged, further evidence of the rushed development cycle of Earthworm Jim 3D.