Invader Zim is an American animated science fiction horror comedy television series created by comic book writer and cartoonist Jhonen Vasquez for Nickelodeon. The series centers on the titular character Zim (voiced by Richard Steven Horvitz), an extraterrestrial from the planet Irk. His mission is to conquer Earth and enslave the human race along with his malfunctioning robot servant GIR (Rosearik Rikki Simons). However, Zim is antagonized by Dib Membrane (Andy Berman), a young paranormal investigator who is determined to stop Zim from succeeding.

Nickelodeon contacted Jhonen Vasquez about pitching ideas for an animated series for their older demographic and Invader Zim was the first thing he pitched. In Vasquez's words "it went from pitch to series without hardly any waiting". As the series went on, ratings declined and budgetary issues became more frequent. Before the second season was completed, Nickelodeon cancelled the series, leaving several episodes unfinished. The show originally aired on Nickelodeon from 2001 to 2002, with six of the completed second-season episodes initially going unreleased. These episodes were first made available on DVD in 2004 and later made their television debut on the Nicktoons Network in 2006.

Invader Zim received positive reviews from critics and audiences, with praise primarily directed at its humor, writing, animation, art-style, and the way it pushed the boundaries of what was considered acceptable on children's television. In the years after its cancellation, Invader Zim has often been listed as one of Nickelodeon's best shows. The series won an Annie Award, an Emmy Award and a World Animation Celebration Award, and received nominations for seven additional Annie Awards and two Golden Reel Awards. Invader Zim has spawned its own fan convention called InvaderCON and a plethora of official merchandise, including video games, toys, clothing and accessories, among many other products. Despite its early cancellation and short run, due to increasing popularity and above-average merchandise sales it has been widely regarded as a cult classic.

A monthly comic book series of the same name was released on July 8, 2015, as a continuation of the television series and published by Oni Press until August 4, 2021. A film based on the television and comic series titled Invader Zim: Enter the Florpus, premiered on Netflix on August 16, 2019.