Roger is a fictional alien character in the adult animated sitcom American Dad!, created, voiced, and designed by Seth MacFarlane. Roger is an anthropomorphic grey space alien living with the Smith family. Having lived on Earth since crashing in Roswell, New Mexico in 1947, Roger came to live with the Smiths after rescuing main character Stan Smith at Area 51 four years prior to the beginning of the series. The character has also made cameo appearances in episodes of Family Guy.

Roger is usually insensitive and careless; he often takes advantage of, cheats, and ridicules people. Over time, the character has also exhibited increasingly sociopathic, cruel, selfish, devious, and depraved behaviours. Due to that, Roger has a love-hate relationship with the Smith family, who care about him despite being his most frequent victims. His most important relationships are with Stan, his best friend, as Stan is annoyed by Roger's antics despite the fact that he saved his life and is the least tolerant of them; Klaus, who is Roger's frenemy; and Steve, who is Roger's partner in many of his misadventures. In early episodes of the show, Roger was disallowed from leaving the Smith house in order to conceal his being an alien. This restriction was soon abandoned and Roger begins adopting disguises and fictitious personas in order to have a life outside the house.

Roger's personas have become a major plot device, with his myriad of alter egos frequently being the subject or facilitator of an episode's main story or subplot. This also helps to amplify his pansexuality and androgynous nature, which varies depending on the plot situation and persona he has adopted. Aside from catalyzing the plot or subplot with his various personas, and despite his increasingly evident self-interest, he often serves to counsel the show's main characters, by humorously affirming or bluntly disregarding their opinions.

When voicing the character, MacFarlane speaks in a swish accent intended to resemble that of Paul Lynde. In April 2014, Roger was voted "Gayest Cartoon Character of All Time" in a first-ever March Madness style competition held by Logo TV.

Roger loves drinking wine. He is currently single and is also pansexual. Roger is slightly shorter than Hayley though he was also described as being 3 foot tall by Stan but this was likely just an insult. Having his feelings hurt usually spurs the creation of his alter egos and schemes. As an alien, Roger displays a multitude of bizarre physical traits, such as superhuman speed, being fireproof, and the ability to generate electricity. When stressed, his body can grow large tumors that, when removed, become fully sentient organisms themselves, as seen with his "son" Rogu.

Roger typically displays a lighthearted, carefree temperament while at the same time engaging in his freakish grossness, outrageous malice, and rascally shenanigans. Crude and brazen, Roger has no qualms with randomly saying and doing whatever is on his mind, having little to no sympathy for anyone who might suffer as a result of his actions, and regularly misleading and finagling others to achieve his desired ends. He will engage in complicated schemes for comparatively minor results, such as nearly marrying a woman he finds intolerable in order to get a new blender as a wedding gift, or getting Stan elected mayor of Langley Falls to construct a bullet train, to persuade Urban Outfitters to construct a store in the city. However, according to the episode "Frannie 911", Roger is not this unpleasant by choice; his species of alien must let all unpleasantries out, for if they don't, it will turn into poison and kill them. He is the best friend of both Stan and Steve Smith, and several subplots revolve around the latter, most notably the Wheels and the Legman episodes. Roger and Steve have a love-hate relationship, in which they constantly bicker and insult each other, but show affection for each other several times.

According to "Frannie 911", Roger has been on Earth for over 60 years, having arrived in 1947 as a result of being tricked, led to believe he was "The Decider" in whose hands the fate of humankind rested, when in fact he was serving the role of a crash test dummy. Earlier, after causing his aunt's spaceship to crash, Roger lived with a family of pioneer fur trappers that died traveling on the Oregon Trail in the episode "OreTron Trail". There is also the possibility, he or another member of his alien race came to earth in early antiquity, evidenced by the premiere of season 13: in the episode, a stone carving is depicted as an alien bearing physical similarities to Roger, the alien squatting above a pyramid with two Egyptians presumably praising him and hieroglyph characters surrounding them. In the episode "Naked to the Limit, One More Time" however, it is evidenced that Roger remains on Earth by will, the episode revealing that he can simply call for his alien kind's spaceship to return him to his birth planet if he so desires.

Details on Roger's actual family and pre-Earth life have yet to be shown on the series. Although in the episode "Lost in Space", a brief clip revealed that prior to Roger's life on Earth, he was involved in a homosexual romantic relationship with another member of his alien race, Zing; however, Roger cheated on Zing, blatantly making out with a human male in front of him. It's also been revealed in the episode "I Am the Walrus" that Roger ate his father when he turned 15. Roger revealed in the episode "OreTron Trail", that he once visited Earth before in the 1800s after crash landing with his aunt Caroline and she died on impact.