Marie wears a black tank-top that halts right above her belly button, a pink belt, green non-camouflaged BDU pants, a dark green wristband on her left arm and black shoes with gray soles. Her overall appearance leads one to believe she is a fan of rock music. She is often shown as crafty and sneaky, especially when compared with her sisters. Her teeth are poor as they're all yellow. Her nails are painted red and she also wears blue eye shadow. She wears a sleeveless green shirt and polka-dotted boxer shorts to bed. Marie appears to have a slight rural Midwestern accent. She has short blue hair that covers her right eye; it is not known whether her hair is dyed this color or comes this way naturally (as is assumed with Rolf).
Marie is an easily angered, intimidating, and rather tomboyish girl. She has a very menacing personality, perhaps best exemplified in "Key to My Ed" when the presence of her and her sisters manages to stop a rumble and scare everyone away from the Lane. She is also shown to be quite strong, as in "Tag Yer Ed" she is able to defeat all three Eds in a wrestling match in less than 20 seconds. She has also been known to easily rip out Lee's armpit hair, rip the covering off of a speaker, and restrain Eddy with nothing more than a pair of underwear.
Like the other Kankers, her anger is feared by all who have seen it. This is exemplified in both "Run for your Ed" and "May I have this Ed?" In the former episode, she and her sisters terrorize the cul-de-sac, causing a humongous wave of destruction comparable to a natural disaster whereas in the latter she (inadvertently) destroys Peach Creek Jr. High in a fit of jealousy brought on by seeing Nazz dancing with Edd. Like her sisters, she is mean to the other kids, and because of this has built up somewhat of a reputation.
While Lee is most often seen as the leader of the sisters, Marie has been known to strike out on her own, and in some cases challenges Lee for command of the trio. Of the three, she is the most rational, countering some of Lee's viciousness and May's stupidity. She is not easily scared and hardly ever backs down; in fact, there is only one known instance where she did back down. This is "A Fistful of Ed," and she backed down after Eddy yelled at her and her sisters for picking on Edd after he lost a fight to Jimmy.
Marie is very crafty. This is largely because she is the most rational of the Kankers. Quite often, she is able to misdirect and mislead people. She is also known as the sneakiest of the Kankers.
Vocally, she doesn't have the deep, grating voice of Lee, nor the somewhat piglike affectations of May. Her voice is somewhat high and girlish, especially when she's excited; however, when enraged or irritated, it takes on a sharper edge and sounds dryer. When she's crying, her voice wavers and she speaks in a higher vocal register.
Although her appearance would suggest that she likes bad boys, her chosen "boyfriend" is Edd. This is odd, as Edd is in no way rebellious and is the most polite person in the cul-de-sac. It's possible that she likes guys who, like her, are somewhat smarter than average. Her liking him is there from her first appearance, however, as are the relationships between her sisters and the other Eds. It's possible that she sees Edd as the most natural counterpart to her, and this may hint at hidden depths. Given her home life and the frequent fighting of the sisters, it's quite possible that she simply carries a lot of stress and simply needs someone who would be willing to care for her. Of course, it's also possible that she likes Edd because he is the most malleable of the Eds, as demonstrated by his willingness to go along with Eddy's schemes no matter what and his willingness to bend over backwards in order to please people and help them out. Not only that, but it's frequently demonstrated that the Kankers like the power they hold over the Eds more than anything else, as in "A Twist of Ed" she was as scared as her sisters by the Eds' change of pace.
Oftentimes, Marie is seen bullying the other characters. The first episode where they're seen bullying someone who's not an Ed is "Dawn of the Eds," where they tie Kevin to a wheel and torture him. Other instances include "For the Ed, by the Ed" and "A Fistful of Ed." In the first one, she joined up with her sisters to bully Jimmy, and in the latter episode, she threatened Jonny with physical violence over a piece of pie. This bullying demeanor is carried over to Ed, Edd n Eddy's Big Picture Show, where she and her sisters are seen bullying Jimmy and, later, torturing both Jimmy and Sarah. They also capture Kevin, Rolf, and Nazz, tie them up, and carry them along on their way to find the Eds.
On occasion, she has shown a soft side, however. Marie is known to enjoy painting, is willing to make Edd a meal, and sometimes makes an actual effort to please her "boyfriend". She is also sometimes seen painting her toenails, and on a couple of occasions has worn a dress.
In "Take This Ed and Shove It", Marie has grown into an ugly, morbidly obese senior citizen. She is still the toughest and trickiest Kanker after 90 years. She is also married to Old Edd and had one child (or grandchild). Old Marie is only shown in a deleted scene from "Take This Ed and Shove It" along with the other older Kanker Sisters.
Marie is one of the NPCs in FusionFall and is located just outside the Trailer Park in Peach Creek Commons. Marie is working on a "Trojan Hamburger" project, wherein she is constructing a giant fake hamburger. The idea is that she and her sisters will hide in it and wheel it down to the cardboard castle. At the gates, the Eds are supposed to mistake it for an actual giant hamburger & unknowingly let them into the Cul-de-Sac. She normally bullies the other kids into helping her work on it, or Lee when she isn't doing anything. She gives multiple missions but does not have a Nano.
In the (now deleted) future, Marie has disappeared from the game. The Trojan Hamburger is seen crashed and broken in the poisoned creek, lying in a pit of stinking Fusion Matter. It is assumed that she, along with her sisters, was a victim of Fuse's invasion.
- Judging from what was shown in "Out with the Old, In with the Ed," Marie adores Tater-tots.
- She and her sisters all wear pink belts.
- Her actions in "A Twist of Ed" indicate that she may have a fear of commitment.
- She claims to "like cheaters" in "Over Your Ed," further backing this up.
- Unlike her sisters, Marie does not behave like the member of the Eds she has a crush on (in this case Edd).
- In Ed, Edd n Eddy's Jingle Jingle Jangle, in the scene where the cracker exploded in the Kanker Sisters' faces, Marie was shown to have an eye patch under her hair, creating questions about their home life. Although this may have been a gag, it raises serious worries. In Season 1, though, all the times we see both her eyes she has no eye patch on. She might have kept the eye patch on from when she and her sisters were pirates in "Avast Ye Eds", or had been wearing it for fun.
- Marie likes cheaters (said in in "Over Your Ed"), slobs (said in "Run for your Ed"), and probably men with muscles (as hinted in "Honor Thy Ed" by the drawing on the trash can Edd was in), but despite this, she chose an educated and well-mannered man such as Edd.
- Marie and her sisters played hooky for a short while until they were mysteriously seen in class again. It is possible they got caught and were forced to stay in their classes to avoid trouble.
- Marie is voiced by Kathleen Barr, who also voices Kevin.
- Marie may have a basic knowledge of the arts, as she referenced Vincent Van Gogh in Ed, Edd n Eddy's Hanky Panky Hullabaloo.
- Big Jim Miller, the head storyboard artist for many of the episodes, thinks that Marie is the cutest girl out of every female character. According to Animation by Mistake, he says that "she has a completely sultry half-lidded smirk." He punctuated this by purring.
- Marie is the only member of the Kanker Sisters to not have a natural hair color (Lee's hair is red/ginger, while May's is blonde/yellow).
- Additionally, Marie and Rolf are the only two characters to not have a natural hair color (along with blue hair). Rolf doesn't seem like one to buy hair dye, making it possible that blue is actually a normal hair color in the Ed, Edd n Eddy universe.
- Marie is the only female that doesn't share a hair color with their voice actor. May and Nazz are both blondes and are voiced by Erin Fitzgerald/Jenn Forgie; Lee and Sarah are both redheads and are voiced by Janyse Jaud.
- In the movie, Marie is seen wearing one of Eddy's shirts. It is never shown how she got it, although it's possible that the sisters stole it from Eddy's closet in "Home Cooked Eds."
- Marie is one of two females in the series to wear boxers. The other one is Nazz.
- Marie, along with Lee and Rolf, are the only characters to have different colored teeth instead of white. Marie has yellow teeth, Lee has yellow teeth along with a blue tooth, and Rolf has green teeth.