20 Movies That Should Have Been Epic Trilogies, And We're Still Waiting For That Third Part

When a film gains popularity, it's easy to see a sequel from a mile away. Sometimes, whether it is box office failure or bad reviews, a movie series with a potential trilogy never makes it past the second movie. These "duologies" are rare, but leave fans annoyed they never got an Act III to the series.

Scene in a theater with people wearing 3D glasses. Foreground character exclaims, "I was meant to see this movie."

Here are 20 film duologies that deserved a third and final installment:

1.Sherlock Holmes & Sherlock Holmes: A Game of Shadows

Robert Downey Jr. in a dark coat and hat faces Jude Law in a tan overcoat and hat in a tense scene against a wooden backdrop

2.National Treasure & National Treasure: Book of Secrets

Nicolas Cage is holding a large, framed parchment in front of a detailed wooden door

3.Hellboy & Hellboy II: The Golden Army

Ron Perlman as Hellboy, an extraterrestrial superhero, aims a large firearm in an intense scene from the movie "Hellboy." His character's horns are sawed off

4.The Princess Diaries & The Princess Diaries 2: Royal Engagement

Anne Hathaway as Mia Thermopolis in The Princess Diaries, wearing an elegant white gown and a sparkling tiara, surrounded by formally dressed attendees

5.Monsters Inc. & Monsters University

Mike Wazowski, a one-eyed green monster, and Sulley, a large furry monster, walk together on a sidewalk in a bustling city scene from Monsters, Inc

6.The X-Files: Fight the Future & The X-Files: I Want to Believe

David Duchovny and Gillian Anderson stand outdoors at night, looking concerned

7.300 & 300: Rise of an Empire

A Spartan helmet and shield, in a battle scene from the movie "300"

8.Kill Bill: Volume I & Kill Bill: Volume II

Uma Thurman, in a bloodstained yellow outfit, stands in a fighting pose surrounded by sword-wielding men in suits and masks in a Japanese-style interior

9.Bladerunner & Bladerunner 2049

Man dressed warmly in a coat, lying on snowy steps outdoors in a storm

10.Gremlins & Gremlins 2: The New Batch

A close-up of Gizmo, the main character from the movie "Gremlins." Gizmo is a furry creature with large eyes and a slightly smiling expression

11.21 Jump Street & 22 Jump Street

Channing Tatum and Jonah Hill dressed as police officers, with Tatum playfully putting his arm around Hill's neck

12.Pacific Rim & Pacific Rim Uprising

Multiple giant robots, including Gypsy Avenger, from the movie "Pacific Rim: Uprising," stand ready in an urban, futuristic setting

13.Charlie's Angels & Charlie's Angels: Full Throttle

Cameron Diaz, Drew Barrymore, and Lucy Liu ride in a speedboat labeled "Donzi" on the water, smiling and wearing sunglasses

14.Tim Burton's Batman & Batman Returns

Batman wearing his iconic suit and mask, looking serious and focused

15.A Goofy Movie & An Extremely Goofy Movie

Goofy and Max from Disney's "A Goofy Movie" sit in a car, looking serious and focused, with rain visible through the window

Both Goofy movies are really good father-son films.

The sequel was a home movie, so why not complete the trilogy with a story featuring Grandpa Goofy and Max as a father? Potential title: "A Goofy Dads Movie."

Walt Disney Television Animation

16.Father of the Bride & Father of the Bride Part II

Diane Keaton, Martin Short, and Steve Martin are fearfully reacting in formal attire, likely at a celebratory event

17.Lara Croft: Tomb Raider & Lara Croft: Tomb Raider — The Cradle of Life

Angelina Jolie as Lara Croft holds a relic while standing in a candle-lit ancient temple setting in a scene from "Lara Croft: Tomb Raider."

It's another popcorn franchise wasted. The movies themselves aren't Oscar-worthy, but they are fun. Angelina Jolie was white-hot at the time and could put butts in seats.

Seeing her make one last Lara Croft in the spirit of how Logan handled Hugh Jackman's Wolverine would be fun.

Paramount Pictures

18.Predator & Predator 2

A dramatic close-up of Predator alien's hands

19.Speed & Speed 2: Cruise Control

Keanu Reeves and Sandra Bullock look concerned on a bus in a scene from the movie "Speed."

20.The Amazing Spider-Man & The Amazing Spider-Man 2

Close-up of Spider-Man's mask and upper body against a blurred background

What film duology do you think should have been a trilogy? Do you still want to see a third film from these franchises? Comment below!