The Creeper (Jack Ryder) is a superhero created by Steve Ditko and Don Segall for DC Comics. He is portrayed as a journalist and talk show host, usually living in Gotham City, who gains the ability to transform into the superhuman the Creeper (and vice versa) thanks to experimental science developed by Dr. Yatz. First appearing in Showcase #73 (March 1968), his origin was revised in Secret Origins (vol. 2) #18 in 1987, then partially revised again in The Creeper #1–4 in 1997, then completely reimagined in the six-issue miniseries The Creeper (vol. 2), published in 2006–2007.

Originally, Ryder's transformation into the Creeper involved activating a device that granted superhuman abilities while also covering his face in yellow make-up, concealing his hair in a green wig, and instantly replacing his clothing with a yellow and red costume with green trunks and a fur-like cape; as the Creeper, Ryder then shifted his voice tone and acted chaotically to intimidate foes and protect his identity. Starting in 1987, it was said Ryder suffered an actual slight change in personality when he became the Creeper, as the device not only empowered him and dressed him in a costume but also altered his brain chemistry. Starting in 1997, Ryder and the Creeper are treated as two personalities sharing the same body. The 2006–2007 miniseries The Creeper (vol. 2) presented a new origin. Starting with this story, Ryder's transformation no longer involved a costume and is depicted as a physical transformation. Along with his strange appearance, the Creeper is characterized by superhuman strength, agility, healing and stamina, as well as a maniacal laugh. Starting in the 1990s, this laugh has been able to cause pain or immobility in enemies. Through experience and training, the Creeper is a formidable fighter and acrobat. In the New 52 continuity, a short-lived incarnation of the Creeper was a villain, not a hero, a malicious oni (demon) who inhabited human hosts to create chaos.

The Creeper is a frequent ally of Batman and has been a recurring character in stories involving him. Outside of comics, the Creeper has appeared in the TV shows The New Batman Adventures and Batman: The Brave and the Bold, and appeared in his civilian identity Jack Ryder in the Batman: Arkham video game series. The Creeper shares visual similarities to the villain the Joker, but originally no connection was intended and the two characters did not meet until 1975, seven years after the Creeper's debut. The New Batman Adventures has the Joker's venom involved in the Creeper's origin, with the comics following suit.

The character first appeared in Showcase #73 (April 1968). Later the same year, the Creeper starred in his own series Beware the Creeper, written by Dennis O'Neil (with Steve Ditko plotting the first issue). It lasted six issues. The Creeper repeatedly fought a chameleonic villain called Proteus, whose true identity was revealed just before his violent death in the final issue.

For the next two decades, the Creeper made sporadic appearances in DC Comics stories, often aiding other heroes such as Batman. Most of these stories were written by Denny O'Neil. The Creeper teamed with Batman in The Brave and the Bold #80 (November 1968), then guested in Justice League of America #70 (March 1969). He also appeared with Batman in Detective Comics #418 (December 1971). After the origin was reprinted in Detective Comics #443 (November 1974), Jack Ryder was shown working as a news anchor on Gotham City television in issue #445 (March 1975). In Detective Comics #447–448 (May–June 1975), the Creeper helped Batman prove he had been framed for murder by Ra's al Ghul.

In 1975, he met Batman's archenemy the Joker for the first time in The Joker #3. The story, which featured a character intended to emulate Peanuts creator Charles M. Schulz, began with the Creeper being mistakenly blamed for a crime the Joker committed due to their similar appearances (specifically, green hair and a maniacal laugh). Later that year, the hero appeared in Super-Team Family #2 and was given a new origin that was not referenced again until later.

The Creeper appeared in a one-off solo story in 1st Issue Special #7 (October 1975), penciled by Ditko. He met Wildcat in Super-Team Family #2 (January 1976) and reunited with Batman in The Brave and the Bold #143 (October 1978) and 178 (September 1981). He and other stars of Showcase appeared in that comic's 100th issue (May 1978). A story intended for the never-published Showcase #106 in 1978 (written and drawn by Ditko) was later included in Cancelled Comic Cavalcade #2 and in The Creeper by Steve Ditko hardcover collection published by DC in 2010. The hero also appeared in back-up stories featured in Adventure Comics #445–447 (1976), World's Finest Comics #249–55 (1978–1979, written and fully drawn by Ditko), and The Flash #318–323 (1983). He teamed up with Superman in DC Comics Presents #88 (December 1985), written by Steve Englehart.

Following the company-wide crossover Crisis on Infinite Earths (1985–1986), DC Comics rebooted large portions of its superhero universe, and many characters were given revised origins or reimagined natures to make them more relevant to modern comic book readers. In Secret Origins (vol. 2) #18 (1987), in a story presented by Andrew Helfer and Keith Giffen, the Creeper was given a new origin and it was now said Ryder's behavior while in costume was not simply an act. In this origin, Ryder is drugged against his will when he is then exposed to Dr. Yatz's technology. Whenever he summons his Creeper costume afterward, a side effect is that his mind reverts to the state it was in when he was drugged, thus causing the Creeper's strange behavior.