1. E.T. the Extra-Terrestrial (1982)
Steven Spielberg’s iconic alien is perhaps the most famous three-fingered extraterrestrial. E.T. has long, thin fingers—two outer fingers and a central digit—though his hands are often described as having a "primitive" but highly functional grip.
2. The War of the Worlds (1953 & 2005)
In the 1953 classic, the Martians are depicted with a single eye and three-fingered hands with suction-cup tips. In the 2005 remake directed by Steven Spielberg, the "Tripod" pilots also maintain a tri-dactyl (three-fingered) limb structure.
3. Close Encounters of the Third Kind (1977)
The "Grey" aliens seen at the end of the film—specifically the one that performs hand signals to communicate—are often depicted in behind-the-scenes models and on-screen shots as having three elongated fingers and a thumb, or just three primary digits depending on the specific puppet used.
4. District 9 (2009)
The "Prawns" (Poleepkwa) have a very distinct crustacean-like physiology. Their hands consist of three main fingers (two primary digits and a thumb-like appendage), which they use to operate their bio-metric weaponry.
5. The X-Files (1993–2002)
Throughout the series, various alien remains and biological "Greys" are shown. While the designs varied, several iterations—particularly the "Purity" virus entities and some of the hybrid remains—were depicted with three or four digits to emphasize their non-human origin.
6. Babylon 5 (1993–1998)
The Vorlons, one of the most mysterious ancient races in the series, appear in their encounter suits with "hands" that feature three large, claw-like mechanical or organic digits.
7. Mass Effect (Video Game Series, 2007–2012)
While not a movie, this massive sci-fi franchise heavily influenced modern alien design. Several major races, most notably the Turians and the Quarians, are strictly tridactyl, having only three fingers on each hand.