An extraterrestrial or alien is a lifeform that did not originate on Earth. (The word extraterrestrial means 'outside Earth'.) Extraterrestrials are a common theme in modern science-fiction, and also appeared in much earlier works such as the second-century parody True History by Lucian of Samosata.
Science fiction (often shortened to sci-fi or abbreviated SF) is the genre of speculative fiction that imagines advanced and futuristic scientific or technological progress. The elements of science fiction have evolved over time: from space exploration, extraterrestrial life, time travel, and robotics; to parallel universes, dystopian societies, and biological manipulations; and, most lately, to information technology, transhumanism (and posthumanism), and environmental challenges. Science fiction often specifically explores human responses to the consequences of these types of projected or imagined scientific advances.
The precise definition of science fiction has long been disputed among authors, critics, scholars, and readers. It contains many subgenres, including hard science fiction, which emphasizes scientific accuracy, and soft science fiction, which focuses on social sciences. Other notable subgenres are cyberpunk, which explores the interface between technology and society; climate fiction, which addresses environmental issues; and space opera, which emphasizes pure adventure in a universe in which space travel is common.
A disguise can be anything incognito which conceals one's identity or changes a person's physical appearance, including a wig, glasses, makeup, fake moustache, costume or other items. Camouflage is a type of disguise for people, animals and objects. Hats, glasses, changes in hair style or wigs, plastic surgery, and make-up are also used.
Disguises can be used by criminals, terrorists, secret agents and special forces operators seeking to avoid identification. A person working for an agency trying to get information might go "undercover" to get information without being recognised by the public; a celebrity may go "incognito" in order to avoid unwelcome press attention. Protests often feature people dressed in humorous costumes while political publicity stunts and pranks sometimes employ disguises and imposture. In comic books and films, disguises are often used by superheroes, and in science fiction they may be used by aliens. Dressing up in costumes is a Halloween tradition.
Doctor Who is a British science fiction television series broadcast by the BBC since 1963. The series, created by Sydney Newman, C. E. Webber and Donald Wilson, depicts the adventures of an extraterrestrial being called the Doctor, part of a humanoid species called Time Lords. The Doctor travels in the universe and in time using a time travelling spaceship called the TARDIS, which externally appears as a British police box. While travelling, the Doctor works to save lives and liberate oppressed peoples by combating foes. The Doctor usually travels with companions.
Beginning with William Hartnell, fourteen actors have headlined the series as the Doctor; the most recent being Ncuti Gatwa, who portrayed the Fifteenth Doctor from 2023 to 2025. The transition between actors is written into the plot of the series with the concept of regeneration into a new incarnation, a plot device in which, when a Time Lord is fatally injured or weakened from old age, their cells regenerate and they are reincarnated into a different body with new mannerisms and behaviour but the same memories. This explains each actor's distinct portrayal, as they all represent different stages in the Doctor's life and, together, form a single lifetime with a single narrative. The time-travelling nature of the plot means that different incarnations of the Doctor occasionally meet. The Doctor can change ethnic appearance or gender; in 2017, Jodie Whittaker became the first woman cast in the lead role, and in 2023, Gatwa became the first black actor to lead the series. The different incarnations wear distinctive costumes; designers include Alexandra Tynan and Barbara Lane.
The War of the Worlds is a science fiction novel by English author H. G. Wells about an attempted invasion of Earth by beings from the planet Mars with much greater intelligence and more advanced weapons than humans. The Martians intend to eliminate mankind and conquer Earth because their own older and smaller world has reached the "last stage of exhaustion". It was written between 1895 and 1897, and serialised in Pearson's Magazine in the UK and Cosmopolitan magazine in the US in 1897. The full novel was first published in hardcover in 1898 by William Heinemann. The War of the Worlds is one of the earliest stories to detail a conflict between humankind and an extraterrestrial race. The novel is the first-person narrative of an unnamed protagonist in Surrey and his younger brother who escapes to Tillingham in Essex as London and Southern England are invaded by Martians. It is one of the most commented-on works in the science fiction canon.
The plot is similar to other works of invasion literature from the same period and has been variously interpreted as a commentary on the theory of evolution, imperialism, and Victorian era fears, superstitions and prejudices. Wells later noted that inspiration for the plot was the catastrophic effect of European colonisation on the Aboriginal Tasmanians. Some historians have argued that Wells wrote the book to encourage his readership to question the morality of imperialism. In the preface to his collected works in 1933, Wells explained: "My early, profound and lifelong admiration for [Jonathan] Swift...is particularly evident in a predisposition to make the stories reflect upon contemporary political and social discussions", adding "The War of the Worlds like The Time Machine was another assault on human self-satisfaction", both being "consciously grim, under the influence of Swift's tradition".
Alien invasion or space invasion is a common feature in science fiction stories and films, in which extraterrestrial lifeforms invade Earth to exterminate and supplant human life, enslave it, harvest people for food, steal the planet's resources, or destroy the planet altogether. It can be considered as a science-fiction subgenre of the invasion literature, expanded by H. G. Wells's seminal alien invasion novel The War of the Worlds, and is a type of 'first contact' science fiction.
Experts consider the prospects of an actual invasion of Earth by extraterrestrials to be extremely unlikely, due to the enormous cost in time and resources.
Space opera is a subgenre of science fiction that emphasizes outer space adventures set in a universe in which faster-than-light travel has become common. The plots often play out against a backdrop of space warfare, alien civilizations and galactic empires. The sub-genre is sometimes thought of as a futuristic homage to earlier adventure sagas, such as those found in mythology and chivalric romance.
The term does not refer to opera music, but instead originally referred to the melodrama, scope, and formulaic stories of operas, much as used in "soap opera", a melodramatic domestic drama, and "horse opera", a 1930s phrase for a clichéd and formulaic Western film. Prototypes of space opera emerged in the early twentieth century, and the genre today enjoys great popularity in literature, film, comics, television, video games and board games.
Science fiction is a genre of speculative fiction that deals with imaginative, futuristic and scientific concepts. These concepts may include information technology and robotics, biological manipulations, space exploration, time travel, parallel universes, and extraterrestrial life. The genre often explores human responses to the consequences of projected or imagined scientific advances.
Science fiction is related to fantasy, horror, and superhero fiction, and it contains many subgenres. The genre's precise definition has long been disputed among authors, critics, scholars, and readers. Major subgenres include hard science fiction, which emphasizes scientific accuracy, and soft science fiction, which focuses on social sciences. Other notable subgenres are cyberpunk, which explores the interface between technology and society, climate fiction, which addresses environmental issues, and space opera, which emphasizes pure adventure in a universe in which space travel is common.
Gamera (Japanese: ガメラ, Hepburn: Gamera) is a giant monster, or kaiju, that debuted in the 1965 film Gamera, the Giant Monster by Daiei Film. The character and the first film were intended to follow the success of Toho's Godzilla film series, while various staffs have participated in both and related franchises, and the two franchises have influenced each other. The Daiei franchise has become a Japanese icon in its own right and one of the many representatives of Japanese cinema, appearing in a total of 12 films produced by Daiei Film and later by Tokuma Shoten and Kadokawa Daiei Studio (Kadokawa Corporation) respectively, and various other media such as novels, anime, videos, manga and cartoons, magazines, video games, television programs, shows, other merchandises, and so on.
Gamera is depicted as a giant, flying, fire-breathing, prehistoric turtle. In the series' first film, Gamera is portrayed as an aggressive and destructive monster, though he also saved a child's life. As the films progressed, Gamera took on a more benevolent role, becoming a protector of humanity, especially children, nature, and the Earth from extraterrestrial races and other giant monsters.
Planets outside of the Solar System have appeared in fiction since at least the 1850s, long before the first real ones were discovered in the 1990s. Most of these fictional planets do not differ significantly from the Earth and serve only as settings for the narrative. The majority host native lifeforms, sometimes with humans integrated into the ecosystems. Fictional planets that are not Earth-like vary in many different ways. They may have significantly stronger or weaker gravity on their surfaces, or have a particularly hot or cold climate. Both desert planets and ocean planets appear, as do planets with unusual chemical conditions. Various peculiar planetary shapes have been depicted, including flattened, cubic, and toroidal. Some fictional planets exist in multiple-star systems where the orbital mechanics can lead to exotic day–night or seasonal cycles, while others do not orbit any star at all. More fancifully, planets are occasionally portrayed as having sentience, though this is less common than stars receiving the same treatment or a planet's lifeforms having a collective consciousness.