Extraterrestrial life, also known as extraterrestrial life (or "extraterrestrial life" or "alien" if it is a sentient or relatively complex individual), is life that occurs outside the earth and may not originate from the earth. These hypothetical life forms may range from simple prokaryotes to more civilized creatures than humans. Drake's equation predicts intelligent life elsewhere in the universe. All kinds of extraterrestrial life sciences are called exobiology.

Since the middle of the 20th century, people have been looking for signs of alien life. This includes the search for current and historical extraterrestrial life, as well as the narrow search for extraterrestrial intelligent life. Depending on the search category, the methods range from analyzing telescope and sample data to radios for detecting and transmitting communication signals.

The concept of extraterrestrial life, especially the concept of extraterrestrial intelligence, has had a significant impact on culture, mainly in science fiction. Over the years, science fiction has conveyed scientific ideas, imagined various possibilities, and influenced the public's interest and views on extraterrestrial life. A shared space is to debate the wisdom of trying to communicate with extraterrestrial intelligence. Some people encourage radical approaches to trying to reach out to intelligent alien life. Others cite the tendency of the technologically advanced human society to enslave or eliminate the less developed society, arguing that it may be dangerous to actively arouse people's attention to the earth