Mandy is a 12-year-old girl who typically has a cynical and arrogant attitude and is the main deuteragonist. Unlike Billy, she is more stable, sane, and intelligent.
Mandy is a morbid little girl with blonde hair that is shaped distinctively like devil horns and for some reason, she has no nose (except two very small nostrils), which characters in the show remarked about more than once.
Her outfit consists of a small, pink dress with a flower in the center, black shoes and a black headband.
Mandy seeks world domination, but when it gets offered to her, she turns it down, because she either wants to do it herself or wait for the right moment. She is incredibly intelligent and will stand up to anyone or anything, which is why she always gets her way.
She hardly ever smiles or has a neutral expression, and it seems she had a frown on her face even before birth. Next to never being pleased by anything, she never smiles because her smile seems to cause the whole universe to implode simply because Mandy smiling is an unnatural occurrence that the universe can’t seem to handle, as shown in the episode “My Fair Mandy.”
She is sworn enemies with the popular school girl, Mindy.
Mandy bosses Grim around constantly and makes him do her chores; she often does the same to Billy as well. According to Billy, she’s afraid of professional figure skaters, but she denies this and simply says, “I just don’t trust the way they spin is all.” In “Billy and Mandy’s Big Boogey Adventure,” her worst nightmare is revealed to be getting old, fat, nice and being married to Irwin.
Unlike Billy, Mandy is rarely responsible for the adventures/troubles the trio often has. In fact, she’s usually right there trying to prevent him from causing more mayhem or simply to solve the problem. Though her “concern” never lasts long; and when it gets out of hand, she just ends up leaving the scene or stop bothering.
It was shown in “Billy and Mandy’s Big Boogey Adventure” that she may have hidden feelings for Billy; as she seemed extremely saddened with near tears in her eyes when thinking he died, and was delightfully surprised when he was shown to be unharmed. She said once, in an effort to help him in “The Bubble with Billy,” she says “Billy, we’ve known each other now for what seems like a nightmarish eternity…. and though I insult and lie to you daily, steal your stuff, make fun of you, your family, or anyone that looks like you, I still don’t feel like I………. know you……….”
It has been said that they love each other, though they do not know it yet.
Nevertheless, they do have a certain relationship, with Billy sometimes calling her “My dear, sweet Mandy.” In the episode “Keeper of the Reaper,” he says “I’ll miss your hands on approach to life.” Mandy nearly always pushes Grim to help Billy saying many excuses to help or save Billy, despite Grim insisting to leave the boy. In “Which Came First?” when Mandy pushed Grim into saving Billy, he said, “Awww… I knew you two were sweethearts,” and then he proceeded to make kissing noises. She then punched him and makes an excuse that Billy owes her $5.00. Also, in the episode “Puddle Jumping,” after Billy disappeared into a “cosmic sink hole” that magically appeared in the bottom of his kiddy pool due to a beam of sun light reflecting off Grim’s scythe and shinning into the pool’s bottom, Mandy insisted that she and Grim go after him and bring him back, claiming that he was her “science project,” even though Grim really wasn’t up much for the rescue. She has also allowed Billy to have physical contact with her, something she usually doesn’t accept from others.
Mandy has almost exactly the same traits of Gaz from Invader Zim, along with her attitude and disposition.
And Now, for my FAVORITE EPISODE EVER!!! (The episode is “Little Rock of Horrors”) Enjoy!