|Age||8 - 10 years old|
|Friends||Violet Heaslip (best friend, multiple episodes)|
Exposition Guy (best friend, one episode)
|Family||Mother (unknown identity)|
|Abilities||Green greed-induced transformation, super strength, size alteration|
|Voice Actor||Pamela Adlon|
The Birthday Girl is a recurring villain in WordGirl.
Eileen is a 10-year-old girl with orange hair who wears a pink dress with blue sleeves on both sides of the top portion of her dress; she also wears a blue bow on her head and a cat necklace around her neck.
Eileen can easily be described as greedy, selfish, self-centered, immature, and sometimes cruel. Usually, she appears to be a innocent little girl to others. She does whatever it takes to acquire anything she may want by using a faux-polite manner, big eyes, and a lisping voice, along with the the statement "Today is my birthday!". Whenever she is denied something she wants, she yells, "Mine, MINE, MINE!", growing in height and turning a deeper shade of green with each yell until the owner of the coveted item hands it over in fear.
Eileen thinks that every day is her birthday (hence why she is nicknamed "The Birthday Girl") and such uses the excuse as a reason to get special treatment from anyone and everyone, usually to great effect. Because she thinks every day is her birthday, she thinks every party is her birthday party, every cake is her birthday cake, etc. She also greatly annoys Becky because of her lisp, using the "w" sound in words instead of “l” or “r”. e.g. "I wearned my wesson," "Today's my biwthday!", "What do bestest-westest fwiends do?". In addition to using it to get what she wants, she also uses her cute charm to get herself out of trouble, as shown in "The Wrong Side of The Law."
- Her powers are based on those of the Hulk, a Marvel superhero; however, unlike the Hulk, her powers are based on greed rather than anger.
- The only way to reverse Eileen's transformation is to trick her into doing something generous instead of greed, although sometimes her greed alone can backfire on her (as seen in "Who Wants Candy?").
- It is currently unknown what Eileen's last name is.
- In her debut episode and Slumber Party Pooper, it is revealed that Eileen loves gold stars.
- Violet was the first person ever to refer to Eileen as "Birthday Girl".
- As seen in "The Rise of Miss Power," there is a possibility that Eileen can transform into Birthday Girl without having to do anything greedy.
- Interestingly, as Eileen transforms into Birthday Girl, her clothes seem to show no signs of tearing apart the bigger she gets.
- The Birthday Girl (episode)
- Slumber Party Pooper
- Tiny Big (cameo)
- Who Wants Candy?
- Monkey-Robot Showdown (cameo)
- The Wrong Side of the Law
- Earth Day Girl
- Birthday Town
- When Chuck's Mom Is Away (cameo)
- Sonny Days with a Chance of Showers
- Crime In The Key Of V (cameo)
- Where Have All The Villains Gone? (cameo)
- The Rise of Miss Power (cameo)
- The Birthday Girl's Monstrous Gift
- Gift Pony (cameo)
- Scary With A Side Of Butter (cameo)
- House Arrest (cameo)
- Say it Again, Eileen
- Fortune Crookie (cameo)
- A Few Words From Wordgirl (cameo)
- Putt With Honor
- Granny's Corner (cameo)
- Can't Touch This (cameo)