Kick-Ass is the name of three fictional characters serving as the title characters and the protagonists of the Kick-Ass series, published by Marvel Comics under the company’s imprint Icon Comics, and by Image Comics, all created by artist John Romita Jr. and writer Mark Millar. The first Kick-Ass, the protagonist of Kick-Ass – The Dave Lizewski Years David "Dave" Lizewski, is an initially 15-year-old high school student and comic book fan whose dreams inspire him to become a real-life superhero dubbed "Kick-Ass", partnering and later training under Mindy McCready / Hit-Girl. The second Kick-Ass, a supporting character in Hit-Girl, Paul McQue, is an initially 12-year-old middle school student bullied at school, whom Mindy recruits after Dave's retirement. The third Kick-Ass, the villain protagonist of Kick-Ass – The New Girl, Patience Lee, is an Afghanistan war veteran and single mother who dons the Kick-Ass costume and mantle to steal money from various crime bosses for her family, before becoming a crime boss/supervillain herself, leading to Mindy hunting her down in Kick-Ass vs. Hit-Girl. In Big Game, Dave comes out of retirement after being granted real superpowers by the Magic Order to take on the joint forces of a time-travelling alien armada from the past and Wesley Gibson's Fraternity of Super-Criminals, before joining the superhero team The Ambassadors as Codename: America.

Dave Lizewski / Kick-Ass is portrayed by Aaron Taylor-Johnson in the feature films Kick-Ass (2010) and Kick Ass 2 (2013) and the video games Kick-Ass: The Game (2010) and Kick-Ass 2: The Game (2014).

Dave Lizewski is a simple ordinary New York City high school student. His mother dies of a brain aneurysm and Dave serves as an anchor to reality for his loving, single widowed father. Dave takes an interest in comic books, which give him the idea to become a real-life superhero. He purchases a suit and mask, which he wears under his normal clothing, and he begins his own personal training before attempting to fight crime. His first attempt fails, with disastrous results as Dave is hospitalized following being stabbed and being hit by a car. Dave lies to his father, claiming he was mugged. He undergoes intense physical rehabilitation, including four operations. He is released weeks later, with metal plates all over his body and with his nerve endings having delayed reactions to pain, making him almost immune to conventional beatings. In spite of considering giving up crime-fighting, he soon returns to the streets. Kick-Ass rescues a man from a beating and fights off the thugs. An onlooker records the incident and uploads it on YouTube, turning Lizewski into an overnight sensation, given the name Kick-Ass.

Kick-Ass becomes an inspiration for hundreds of people, most of whom are content to simply make web pages and costumes, but some of whom actually go out and effectively fight crime. Kick-Ass encounters two other crime-fighting heroes who call themselves Hit-Girl and Big Daddy, whose level of professionalism intimidates Kick-Ass and also serves to remind him just how serious crime-fighting can be. He retires from crime-fighting for a little while until he becomes aware of another hero, who calls himself Red Mist, who has become a sensation, even stealing all the credit for being the first-ever superhero. Kick-Ass subsequently leaves retirement, initially to challenge Red Mist, but instead, they team up. As they drive off they come across a burning building. Kick-Ass overhears a woman saying that her "baby" is still inside. Kick-Ass bravely enters the building with Red-Mist to rescue the baby, only to find out it is a cat called "Baby"; they rescue it and return it to its owner.

Red Mist, however, turns out to be the son of mob boss John Genovese which leads to Big Daddy's death and the torture of Kick-Ass at the hands of various gangsters. Before long, Kick-Ass is rescued by Hit-Girl and the two get their revenge on John Genovese, together bringing down his entire organization. Kick-Ass shoots John Genovese's genitals off with a gun through a pure fluke, giving Hit-Girl an open opportunity to kill John Genovese with a cleaver. After the loss of Mindy's father, Dave drops her off at her mother's house. Dave returns home to find his father having sex with his teacher (whose boyfriend Hit-Girl had killed) on the couch.

Hit-Girl subsequently takes on Kick-Ass as her crime-fighting partner, training him and using him to hunt criminals together with her. She also gets him to teach her how to be a normal kid, and get along with other girls somewhat older than herself.

Dave returns to training and fighting crime in New York City and is now being trained by Hit-Girl. Kick-Ass joins a new superhero team calling themselves Justice Forever, which includes his friends Marty and Todd, and his new crime-fighting ally, "Doctor Gravity". Led by the repentant born-again Christian "Colonel Stars", the group launches a campaign against the local crime families of the city. He now works frequently on gang-busting with his new-found team, as well as his long-time friend Marty as "Battle Guy", sharing inside crime-fighting jokes with him during his school life. He and the team break into a bar and apprehend a gang. Dave goes home to see that his dad has found his Kick-Ass costume and isn't happy about it. They argue about him being a hero, which leads Dave to storm out of the house.

The massacre leads the police (led by Detective Vic Gigante, who secretly works for the Motherfucker as a mob informant) to scapegoat the super-heroes for the deaths. All known heroes are rounded up and put into police custody, including the members of Justice Forever. Kick-Ass avoids arrest due to his father, who discovers his son's super-hero alter ego, much to his horror. Despite his disapproval, Kick-Ass's father turns himself in to the authorities to save his son from arrest. Shortly after, he is attacked by mob henchmen of the Motherfucker, who kill him as part of the villain's campaign to torment his rival. The Motherfucker then attacks the funeral, detonating a bomb in Kick-Ass's father's coffin and has gunmen open fire upon the crowd of mourners, including Hit-Girl and her family. In response, Hit-Girl springs into action to kill the henchmen who kidnap Kick-Ass in the confusion.