Yes , aliens are often prominently featured in Science Fiction ; for example "The Silke" by A.E van Vogt .
Aliens i would say
Sci Fi Science Physics of the Impossible - 2009 Aliens Attack was released on: USA: 3 April 2011
reality
Hi-Fi Sci-Fi was created in 1993.
Aliens Illegal - 2013 was released on: USA: 28 June 2013 (Roswell International Sci-Fi Film Festival)
The film combines elements of both Westerns and Science Fiction films .
Alien (1979) and Alien (2003) are both rated R for sci-fi violence/gore and language.
Sci Fi Inside Sci Fi Friday - 2005 TV was released on: USA: 11 July 2005
"Invasion of the Saucer Men" (1957). Also known as "Invasion of the Hell Creatures"
A moon supposedly circulating a sci-fi planet.
Sci-Fi-London was created in 2002.
Avengers in Sci-Fi was created in 2002.