Guitar Hero is a series of rhythm video games published by Activision in which players use guitar-shaped controllers to mimic the playing of numerous rock music songs in a score attack gameplay; later games in the series have included support for drums and vocals and playing as a full band. With over $2 billion in total sales worldwide, the game series has made a significant cultural impact (especially during the series peak in popularity and relevance in the late 2000's to early 2010's), becoming a cultural phenomenon and recognizable in the popular culture. The series has been found to influence younger players into learning real instruments and has found application within the health care industry to help recovering patients.

Both Guitar Hero and Rock Band (a similar series of games developed by Harmonix, who originally developed Guitar Hero), have altered the video game and music industries. For video games, the introduction of Guitar Hero has led rhythm games to become one of the industries' largest growing markets. The series has also sparked the creation of both commercial and independently developed games with similar gameplay mechanics as well as learning tools using a real guitar in place of the controller. Older artists featured in Guitar Hero and Rock Band have experienced a surge in the popularity of their music, and the games have been seen as a way for younger audiences to experience the classic rock songs featured in the games. Newer bands and unsigned artists have also found success by being included in the game. This has led several bands to seek placement of their songs within the games. The impact of Guitar Hero on the music industry has caused music publishers to re-evaluate their approach to music licensing and their relationship with the video game industry.

In entertainment The series' titles became popular party games, which led them to be played in a variety of locales. In the wake of the series popularity several bars in the United States and Canada began offering "Guitar Hero nights" as an alternative to karaoke; one New York City bar experienced triple the business on such nights. Many concert tours, including the Family Values Tour feature Guitar Hero booths and contests between sets. Guitar Hero is responsible for introducing people to rock music and inspiring them to learn how to play guitar. A study by Youth Music found that 2.5 million out of 12 million children in the United Kingdom have begun learning how to play real instruments after playing music video games such as Guitar Hero; the group believes that these video games can be incorporated into music educational programs. Activision has teamed with the United Service Organizations to provide monetary support and copies of Guitar Hero III to the United States Armed Forces around the world.

In health and treatment Guitar Hero has proven to be a useful tool in the development of children and as recovery for various injuries. Salon.com states that the games helped an 8-year-old guitarist learn sensitivity to rhythm, as well as develop the dexterity and independent hand usage necessary to play the instrument. Guitar Hero has been used alongside physical therapy to help recovering stroke patients as the games help with multiple limb coordination between fretting and strumming. Blondie drummer Clem Burke has worked with researchers at the University of Chichester and the University of Gloucestershire to determine how games like Guitar Hero can address issues of "child and adult obesity, autism, stroke patients and health and mental well-being in the workplace". Researchers at Johns Hopkins University have used Guitar Hero III and its controller to help amputee patients and to develop new prosthetic limbs for these patients. Researchers at Nevada Reno University have been able to modify a haptic feedback glove to work with the Guitar Hero freeware clone, Frets on Fire, to create Blind Hero, a music game that works on touch and audio to appeal the game to visually impaired players. Guitar Hero was used as part of a Trent University youth sleep study which showed that players generally were better at replaying a song they had just been introduced to twelve hours later if that period included normal sleep.

On the video game industry Activision stated on January 21, 2008, that North American sales from all of the Guitar Hero franchise have exceeded one billion dollars with over 16 million units sold, excluding downloadable content. Over 20 million songs have been sold as downloadable content as of July 2008, and 34 million by May 2009. As of October 9, 2008, the series has sold 23 million units with sales of US$1.6 billion, and as of May 2009 has earned US$2 billion at retail. Activision claims that Guitar Hero is the third largest video game franchise after the Mario and Madden NFL series, and is present in over 15 million households. Guitar Hero: World Tour along with other music games such as Rock Band 2 have surged the video game market in 2008; NPD Group reports cited that music video games made up 19% of the overall software industry sales in July 2008, and 16% through November 2008, and contributing to a 32% year-to-date sector growth through July 2008. Total sales of music games doubled in 2008, with total sales of US$1.9 billion. Guitar Hero represented about half of that figure, with a total of $992M of retail sales in 2008, and was the highest selling brand of the year. At the 2009 Consumer Electronics Show, Activision CEO Mike Griffith stated that Guitar Hero III is the first video game to exceed one billion dollars in total sales. Activision reported that the Guitar Hero franchise had 55% of the United States and European markets during the first quarter of 2009. Analysts expect 2009 to be a critical year to determine the future direction of music games, whether the sector will continue to grow or will remain stagnant. Early analysis of the first half of 2009 showed that sales of both Guitar Hero and Rock Band franchise games were down by half from the same period in 2008, likely due to fewer purchases of the more expensive game bundles that include one or more controllers, as well as large discounts on the prices of older games. Viacom, parent company of MTV Games, reported a 32% drop in 2009 second quarter profits, partially driven by weak sales of Rock Band amid the poor economy of the period.

The series has created a market for products outside of the video games. McFarlane Toys has developed a series of six-inch-tall figurines based on the characters from the game. Brett Ratner, director for Rush Hour and X-Men: The Last Stand, has stated that he wishes to bring a movie based on Guitar Hero to theaters. However, Activision, the publisher of the series, did not approve the idea of a film adaptation.

The popularity of the Guitar Hero series has led to the development of several commercial and independent clones. Besides Harmonix' Rock Band series, Konami released Rock Revolution in 2008 which features drums and guitar (the game does not include vocals) similar to Guitar Hero World Tour. PopStar Guitar for the PlayStation 2 and Wii systems, developed by XS Games, features gameplay similar to the Guitar Hero series, but features pop music, as opposed to rock and metal. Digital Praise released a Christian rock-themed guitar-based game called Guitar Praise also in 2008. Guitar Rising, published for personal computers by Game Tank by 2009, is based on using a real guitar in order to perfect one's skills. We Rock: Drum King is a game promoted by Rolling Stone for the Wii that uses two Wii remotes as virtual drumsticks. Frets on Fire is an open-source clone of Guitar Hero for personal computers that features freely available independent songs and allows users to create their own note tracks, Clone Hero features the same aspects of freedom of song choice and community-made note tracks, but aims to almost exactly recreate Guitar Hero, rather than imitate it. Other games based on Guitar Hero include Battle of the Bands and Ultimate Band. Guitar Hero has also influenced other games outside of the music game genre. Tim Schafer credits Harmonix and the first Guitar Hero game to help establish his pitching of his heavy metal-inspired game, Brütal Legend, due to the increase in popularity of metal music from the success of Guitar Hero. Guitar controllers have been repurposed as controls for an independently developed platform game, Fret Nice. Rock of the Dead for the Wii is based on combining the aspects of The Typing of the Dead with using a Guitar Hero guitar controller to fend off zombies. A PlayStation Home themed space based on Guitar Hero, called "Guitar Hero: Backstage", was released on March 26, 2009, in North Americas version, and includes a "Simon says"-like minigame called "Guitar Hero-Master of Rock", themed objects, and videos for the user.

Guitar Hero has also been considered to have made the use of special peripherals more commonplace and acceptable for consumers for games that followed, including Nintendo's Wii console and games such as Mario Kart Wii and Wii Fit.

Fan sites have also arisen to provide news and forums related to the Guitar Hero series. Scorehero is one such site that includes both forums and informal tracking of players' scores for both the Guitar Hero and Rock Band series; the site has received donations from Harmonix president Alex Rigopulos, and site members have been invited to pre-release demonstrations of upcoming games, often leading to information about tracks in these games.

Guitar Hero now holds a place in the Guinness World Records in their Gamer's Edition, tracking the highest score on a single song (Dragonforce's "Through the Fire and Flames") in Guitar Hero III; the record has held by both Chris Chike and Daniel Johnson, each outdoing each other in subsequent attempts; Johnson is the present holder of the record. Chike has received additional notice for performing a full combo playthrough of Dragonforce's "Through the Fire and Flames". Both players' reputations have earned them spokespersons deals, Chike for The Ant Commandos, a third-party peripheral controller maker, and Johnson for eMazingGaming.com, a video game event promoter. Guinness also awarded the series ten world records in the Gamer's Edition 2008, including "Best Selling Guitar Based Game" and "Biggest Funeral for a Fictional Object", when in November 2006 a funeral for the air guitar was held in London, England as a publicity stunt for Guitar Hero IIs release.

On the music industry