Alien seeds hitch a ride to earth in a space shuttle crew and begin to grow. When their numbers reach the Threshold amount they will be an unstoppable swarm.
Signsalien invasion
War of the Worldsalien invasion
Impostoralien invasion
Starship Troopersalien invasion
The Hitchhiker's Guide to the Galaxyalien invasion
The Invasionalien invasion
The Arrivalalien invasion
They Livealien invasion
Independence Dayalien invasion
Bugoniaalien invasion
Disclosure Dayalien invasion
Avengers: Endgamealien invasion
The Darkest Houralien invasion
Color Out of Spacealien invasion
QuarantineSame director
Extinctionalien invasion
Homealien invasion
Body Snatchersalien invasion
The Day After TomorrowSame genre & era
The Tomorrow Waralien invasion
Men in Black: Internationalalien invasion
CoherenceSame genre & era
The Adventures of Buckaroo Banzai Across the 8th Dimensionalien invasion
Mars Needs Momsalien invasion