Agent Wendy Pleakley is an alien from the planet Plorgonar and his species is Plorgonarian. He formerly worked for the Galactic Federation and acts as its expert on the planet Earth, when in reality he doesn't know much. He reluctantly becomes Dr. Jumba Jookiba's partner when forced to assist him in capturing the escaped Experiment 626, and later becomes his best friend and roommate when the two are marooned on Earth.
In contrast to Jumba Jookiba, who enjoys engaging in mad science, Pleakley is very friendly and gentle. Even before joining Lilo's family, he was desperately trying to keep her safe from Jumba's reckless attempts to capture Stitch. His gentle nature makes him the one to help out with more sensitive issues. Despite this, he is usually the first one to start crying in highly emotional or frightening situations. He also has an incredible love for Earth, and does everything he can to protect the planet and its inhabitants, especially the mosquito population, which he believes is an endangered species.
In Lilo & Stitch, due to him wishing to protect Earth's inhabitants, he was called upon to assist mad scientist Dr. Jumba Jookiba in tracking down Experiment 626, which had escaped to the planet Earth. He and Jumba were both fired and sentenced to a prison term on Earth by the Grand Councilwoman of the planet Turo, for failing to capture Experiment 626. In the subsequent TV series, Pleakley and Jumba have remained behind on Earth, and Pleakley has become a member of Lilo's ʻohana, or extended family.
In one episode of the series, he had a brief mock engagement with Nani to placate his pushy visiting mother. In this same episode, he also had a mock engagement to Jumba. Pleakley's mother is concerned that he hasn't found "the right girl" and that he is not married. Pleakley feels he must pretend to be married for his mother to approve and accept him. When his family arrives on Earth for the mock wedding of Nani and Pleakley, he reveals that he is happy being who he is, which includes being unmarried. After that, his family becomes more understanding of him and loves him for who he is.
In another episode, Gantu fell in love with him (under the influence of one of Stitch's cousins), mistaking him for a girl. An entire room full of people fell in love with him because of the experiment at the Valentine's dance; however, Lilo's friend Keoni was the only one to have a real crush on him (which didn't last long).
Ultimately in Leroy & Stitch, as a reward for his help in capturing and taming Jumba's experiments, he is granted a position at Galactic Alliance Community College as Head of Earth Studies. He gets an assistant (who is excited to learn he's actually been to Earth), a new wardrobe, and the keys to the college's car pool van, but is only a supervising professor and is dissatisfied with not being able to spread his knowledge of Earth and starts to miss Jumba and the rest of Lilo's family. He goes to visit Jumba in the GACC van, but gets caught by Hämsterviel and nearly sent into a black hole which Stitch manages to save himself, Pleakley and Jumba from. He returns to Earth for the battle with Leroy and his clones and operates the lights during Lilo and Stitch's impromptu "Aloha ʻOe" concert (accidentally blinding himself at first). He later quits his job at Galactic Alliance Community College and returns to Earth to be part of Lilo's family once again.
Pleakley is a thin lime-green alien with three stout legs with two toes on each foot, a wide mouth with two purple tongues, three elongated fingers on each hand, a round bald head topped with a single small antenna that acts as an ear and nose, and one large eye in the middle of his face. His body shape and style of movement resembles the enchanted brooms from The Sorcerer's Apprentice sequence of Disney's Fantasia. He stands 5 feet 7 inches tall.
In "Poxy", much of the workings of Pleakley's internal system are revealed when Lilo and Stitch shrink themselves and enter it to retrieve an infectious experiment. He has no skeletal system and has an extremely small brain (smaller than his eye; Jumba once said that Pleakley has "too much eye, not enough brain."). His clinic number is 236. In "Mr. Stenchy", his antenna is shown to be a form of sensory organ similar to a human nose (although it functions somewhat differently, allowing Pleakley to ignore or appreciate odors which a human would consider noxious or horrible). In "Yaarp", it is also shown to function as an ear. In "Spike", Nosy reveals that Pleakley dyes his antenna to match his skin because he is going prematurely orange.
- Pleakley's antenna is shown to act like a type of sensory organ similar to a human's ear and nose.
- In "Mr. Stenchy", when it comes to scents, his antenna functions somewhat differently, allowing him to ignore or appreciate odors which a human or other individual would consider noxious or horrible, as Pleakley found Mr. Stenchy's odor appealing, while Lilo, Stitch, Jumba and Gantu were repulsed by it.
- In "Spike", Nosy revealed that Pleakley dyes his antenna green to match his skin because he is going prematurely orange.
- Pleakley bears a great resemblance to Om Nom from the popular mobile video game series Cut the Rope.
- Pleakley was slated to appear in the video game Kingdom Hearts: Birth by Sleep, but was dropped from the final game for unknown reasons, though he is found in the game's coding, albeit without textures.
- Pleakley appears, along with several other Lilo & Stitch characters, in a parody of the Disney Channel Original Movie High School Musical, which was broadcast as part of the High School Musical: Around the World one-year anniversary special.
- Ironically, despite being effeminate, he hates his first name "Wendy", which is a female name. According to his mother, it means "brave warrior" in Pleakley's native language (his brother Bertley wanted that name).
- A running gag in Lilo & Stitch: The Series features Pleakley cooking Thanksgiving dinner, which he believes happens once a month.
- In "Phantasmo", Pleakley is revealed to have upper teeth when he was screaming.
- It is revealed in "Slugger" that Pleakley is an excellent basketball player because he used to play a sport virtually identical to it on his home planet of which he was a champion.
- According to "Mrs. Hasagawa's Cats", when Pix, a camera-like experiment, takes a picture of Pleakley's mouth, it is revealed that not only does he have two tongues, he also has two uvulas.