Grendel is a long-running series of comic books originally created by American author Matt Wagner. First published by Comico, Wagner has now moved his character to Dark Horse. Originally a noir comic concerning a criminal mastermind, it has evolved into, in Wagner's words, a study of the nature of aggression.

The first Grendel was Hunter Rose (Wagner has hinted of previous Grendels in history, but Rose is the earliest which he has written about), a youthful genius who wrote novels by day and ran a criminal empire by night. He first appeared in 1982 in the anthology Comico Primer, and was given his own series in 1983. This was quickly cancelled due to financial troubles the company went through. Wagner, who still owned the character, used the opportunity to re-tell the story of Hunter Rose in a far less conventional style in Grendel: Devil by the Deed, serialised as a backup story in Wagner's series Mage; this was subsequently collected as a 48-page one-shot. Many people consider Rose the most important Grendel; Wagner returns to Hunter Rose from time to time, such as in the two Batman-Grendel crossovers, and occasional miniseries or short stories.

There followed an ongoing series, which lasted 40 issues. It was written by Wagner and drawn by a variety of artists, including the Pander Brothers, Bernie Mireault, Tim Sale, John K. Snyder III and others. It began with a story set in the near future, with Hunter's granddaughter Christine Spar taking on the identity of Grendel to pursue a mission of revenge, but ultimately being consumed by it. The identity passed briefly, and tragically, to her deluded boyfriend Brian Li Sung. After a brief return to stories of Hunter Rose (actually two fictional novels written by Captain Wiggins, a supporting character from the Christine Spar arc), Wagner then spun the series further into the future, with the Grendel identity affecting a variety of people, and ultimately a whole society.

The publishing rights were tied up for several years after Comico's bankruptcy, but Grendel resurfaced at Dark Horse Comics with the ten-part series, Grendel: War Child, written by Wagner.

Following this, Dark Horse launched Grendel Tales, stories set in the world established by Wagner, created by other writers and artists, including Darko Macan and Edvin Biukovic. The main story has also continued in novel form, written by Greg Rucka.

In the years since the publishing of War Child, Wagner has occasionally written short stories featuring Hunter Rose, and most recently launched an eight issue mini-series, Behold the Devil, which is to fill in a secret of Hunter Rose. Behold began publishing in November 2007.