|Aliases||Princess Dee Dee, Stupid Sister, Blockhead, Golden Haired Angel, Pink Pussy Willow, Racer D, Diva Dynamite|
|Family|| Dexter (Brother) |
Grandpa (Maternal grandfather)
Fergle O'Reilly (Maternal uncle)
|Occupation||Ballet Dancer, Student|
|Interests||Pony Puff Princess, Ballet, Dexter's Lab|
|Voiced by|| Allison Moore (season 1)|
Kat Cressida (season 2)
Allison Moore (season 3)
Kat Cressida (season 4)
Dee Dee is a main character and the secondary protagonist in the series, Dexter's Laboratory. She is Dexter's older sister, who is mostly seen destroying or ruining Dexter's lab in various ways. The daily events surrounding Dee Dee's life mainly revolve around her relationship with her brother and everything that happens between the two.
She is two to three times taller than Dexter and has peculiar body proportions; a minuscule torso with a large head and gangly limbs, similar to a ballerina's. To complete the ballet look, she wears a rose/brink pink colored small tutu, white pantyhose and pink ballet pumps, which usually create a "squishy" noise while walking. She has a similar personality and hair color to her father. For sleeping she wears a pink nightgown, and she wears her hair down. For swimming she wears a pink one-piece swimsuit and a pink swimming cap with the initial 'D' on the front. She has fair skin, blue eyes and long blonde hair in pigtails.
Dee Dee is Dexter's extremely ditzy, simple-minded, energetic, hyperactive older sister. She usually, in one way or another, sabotages his experiments and destroys his lab in every episode of the show, although she does so out of ignorant curiosity rather than malicious intent and she in actuality loves and cares for her brother dearly. Though she was shown to get hypocritically angry when she found that Dexter had been in her room and messed with her stuff. Dee Dee also loves ballet, puppies, unicorns, playing dolls with her friends, messing around in Dexter's laboratory and generally depicts all the stereotypes concerning normal girl activities. Her catch-phrase is "Oooooooh, what does this button do?". She rarely wears her full length of hair down except on rare occasions, mostly when sleeping. She also has a multitude of stuffed animals and she has a four poster bed. It was revealed in the episode "A Hard Day's Day" that Dee Dee's astrological sign is Cancer indicating that she was born somewhere between June 22nd or July 23rd. Despite her usual ignorance and apparent stupidity, Dee Dee has been shown to actually be a very wise girl for her age who displays far better common sense than her brother and less naivety about subjects that Dexter is completely ignorant about. Dee Dee has a far better understanding of nature and inner peace than her brother as well apparent knowledge of important biological and botanical subjects, being very familiar with the achievements of biologist and friar Gregor Wendell who even Dexter was completely ignorant of. In the end, Dee Dee is a loving girl with a strong love for her brother and despite his attitude towards her and attempts to get rid of her and even destroy her, she has continued to stick by him long into her elderly years.
While Dee Dee lacks Dexter's skills in technology and science, she has shown to posses a powerful imagination that can even bring imaginary creatures to life, and she can even travel to the imaginary world of Koosland and interact with imaginary creatures such as the Koosalagoopagoop. In seasons 3 and 4, she is also made the creator of Koosland. Dee Dee has also displayed the unusual ability to see into the future as revealed in "Chubby Cheese" and communicate with certain animals.
Although she seems to be extremely ditzy, her social skills far exceed Dexter's, as she is quite popular at their local school while he is shunned by everyone with the exception of his other equally geeky associates.
- Dexter - Dexter is Dee Dee's little brother. She loves "playing with," him but she destroys things in his lab and drives him crazy. It may seem that Dee Dee is nothing but a pure idiot who just annoys Dexter all the time, but truthfully deep down inside of her candy canes and lollipop glitter heart, she loves Dexter and thinks he's awesome. In fact, to her, Dexter is her favorite thing in the whole entire world. This was seen in the episode "Game Show" where the Game Show host asked what their favorite things in the world were and Dexter is what Dee Dee chose. When Dee Dee comes into the Laboratory, she never wants to destroy any of his inventions or ruin any of his experiments. What she really wants out of all that, is to spend time with her little brother Dexter and to spend time with him in their early years of that short and brief section of life called childhood. Dee Dee is really a lot smarter than she comes on to be, Dee Dee is really a smart girl and she is smart enough to know that if Dexter doesn't get out of his lab more often and see the world, he will have wasted his life trapped inside of his lab. Sometimes she wants him to come outside which she does and clearly explains in various episodes such as Way of the Dee Dee. She wants him to see the world and realize what a wonderful and perfect thing life is and to have him experience the best things in life and a lot of the time, Dee Dee's reckless little antics are actually the things that make Dexter do those good things in life. It may be possible that she does this intentionally because she knows what the outcome would be, some would even say she is smarter than Dexter.
- Lee Lee & Mee Mee - Lee Lee and Mee Mee are Dee Dee's two best friends in the series. Their two young girls that share her interests, personality, fashion sense, and even similar names. Dee Dee, Lee Lee, and Mee Mee are just like each other. They always spend their time just being girls and having fun. The three of them all go to the same ballet classes together where they are the three best students with Dee Dee being the best, Mee Mee being the second best, and Lee Lee being the worst.
- Dad - Dee Dee is very close to her father, and it appears that both she and Dexter are closer to their father than with their mother as they are often seen sharing and doing more activities with him than with Mom. While Dad has shown to prefer Dexter over Dee Dee on several occasions, he is clearly more proud of Dee Dee's sports-based accomplishments and her willingness to play sports with him, showing that he cares for her just as much as Dexter. However whenever he goes into his psychotic muffin episodes, he and his children become quite distant.
- Mom - Dee Dee loves her mother as much as her father and Mom has shown to become quite angry at Dexter when he refuses to play or take care of her sister, showing that she cares quite a lot about her, however, like with Dexter, she will not hesitate to scold and punish Dee Dee angrily should she question her or behave questionably. Mom has also shown to be quite proud of Dee Dee's dancing ability and even attends her ballet recitals.
- Koosalagoopagoop - Koosy is Dee Dee's imaginary best friend whom she loves to play with and both often have adventures together and Koosland. Dee Dee is the only one who can see Koosy because she is the only one who believes in him. He is completely invisible to others unless she makes them believe which she did to Dexter.
- Lalavava - Lalavava is Dee Dee's worst enemy. The way she and her act toward each other is just about a mirrored relationship to that of Dexter and Mandark's. However they eventually managed to end their rivalry on a good note unlike their brothers after agreeing that they both hated their brothers and their destructive science. They then became good friends and went to the mall together.
- Oceanbird - Oceanbird once hired Dee Dee to babysit Mandark. She likes her and thinks of her as a friend to the family despite her rivalry with Lalavava.
- Monkey - Whenever Monkey is not in his secret supehero form, he pretends to be an ordinary lab monkey. Dee Dee is sometimes seen playing with Monkey and dressing him up in girly costumes and having tea parties with him despite him being a male monkey. Monkey doesn't seem to be bothered by this and appears to enjoy playing with her as it is one of the few times where he can happily goof off and have fun aside from his dates with Agent Honeydew.
- Beau - Beau is Dee Dee's love interest and ex-boyfriend. He was first seen in the episode Beau Tie.
Originally voiced by Allison Moore, the role was assumed by Kathryn Cressida after the first season. Moore reprized the role in the third season, with Cressida taking it back for the show's fourth season. Tara Strong, who voiced Bubbles from The Powerpuff Girls, voiced Dee Dee in the MAD episode, Once Upon a Toon.
- "Hi Dexter!" - Various Episodes
- "Ooooooh! What does this button do?" - Various Episodes
- "Good Night" - Various Episodes
- "Oh Dexter, Dexter come quick! You sent me, and me!" - Dee Dee Dimensional
- "But I want to push the button." - Dexter's Assistant
- "Your club is for big I D K S C's" - Decode of Honor
- Don't be silly! I love you very much! - LaBretto
- Oops! I guess I shouldn't touch! - LaBretto
- "Play with you Dolly Susie" - Babe Sitter
- "Fine! I don't need your stinkin' lab, i've got my own stinkin' lab!" - Dee Dee's Lab
- "Hello, dear brother! What have you got there? - LaBretto
- Dee Dee's favorite color is pink.
- Dee Dee's birthday was never mentioned, however she mentions she's a Cancer.
- Her feet are very large, this is addressed throughout the series, and in the episode "Shoo Shoe Gnomes" she is seen to have high-rampant foot odor.
- A running gag in the series is Dee Dee showing Dexter her "new" dance called "the Fanciful Unicorn" over and over again, forgetting she has already showed him many times.
- Dee Dee has two friends named Lee Lee & Mee Mee who both look like her and have similar sounding names.
- She has been called a "golden haired angel" by both Mandark and Nice Dexter.