Influences

PRIMARY (franchise core):

• Alien (1979)
• Aliens (1986)
• Alien 3 (1992)
• Prometheus (2012)
• Covenant (2017)

SECONDARY (canon-adjacent space horror/sense of wonder/military sci-fi):

• 2001: A Space Odyssey (1968)
• Saturn 3 (1980)
• Outland (1981)
• Blade Runner (1982)
• The Thing (1982)
• 2010: The Year We Made Contact (1984)
• Akira (1988)
• The Abyss (1989)
• Starship Troopers (1997)
• Contact (1997)
• Event Horizon (1997)
• Starship Troopers 3: Marauder (2008)
• Avatar (2009)
• Pandorum (2009)
• Apollo 18 (2011)
• Almost Human (TV, 2013)
• Interstellar (2014)
• Humans (TV, 2015 - 2018)
• Arrival (2016)
• Westworld (TV, 2016 - ?)
• Ghost In The Shell (2017)
• Life (2017)
• Blade Runner 2049 (2017)
• The Cloverfield Paradox (2018)
• Alita: Battle Angel (2019)
• Ad Astra (2019)
• Underwater (2020)
• Raised by Wolves (TV, 2020)

TERTIARY (pulpy alien stories that might fit the canon): 

• Predator (1987)
• Predator 2 (1990)
• Alien Resurrection (1997)
• Alien vs Predator (2004)
• Alien vs Predator: Requiem (2007)
• Predators (2010)
• Predator: Dark Ages (2015)
• The Predator (2018)