The Alien Parasites are an unnamed group of aliens who invade and conquer planets by shape-shifting into the forms of various beings such as humans, aliens, animals, historical figures etc. and taking up a persona of them.
When alien parasites arrive on a planet, they implant people's minds with false memories of invented characters being people such as friends, family members, etc. Once they have multiplied enough, they use this to take over the planet and enslave the race. They invaded Earth and confronted the Smith family.
- “"These telepathic little bastards embed themselves into memories and multiply to take over planets! They're disgusting, so be careful of any wacky or zany characters that pop up".”
- —Rick explaining the parasites[src]
As Morty discovered, the parasites only implant perfect, friendly and happy memories into their victims. This means if someone cannot remember any bad memories of another person, the latter could be a parasite.
They also seem capable of suppressing other memories, particularly ones contradictory to memories they have implanted. One of the characters created, Sleepy Gary, replaces Jerry as Beth's husband (and possibly Morty and Summer's father), and for this to work any memories of Jerry as Beth's husband would need to be suppressed.
- Uncle Steve
- Cousin Nicky
- Mr. Beauregard
- Frankenstein's Monster
- Sleepy Gary
- Photography Raptor
- Amish Cyborg
- Reverse Giraffe
- Ghost in a Jar
- Baby Wizard
- Mrs. Refrigerator
- William Shakespeare
This is a list of forms that the parasites have taken, but were not named:
- Bear Parka-Wearing Bird - It is one of Tinkles' friends.
- Bearded Lady
- British Guard
- Butterfly/Sunflower hybrid - It is one of Tinkles' friends.
- Chowder Look-A-Like - It is one of Tinkles' friends.
- Cloud Yeti - It is one of Twinkles' friends.
- Duck With Muscles
- Easter Bunny Monkey Critter - It is one of Tinkles' friends.
- Elvis Impersonator
- Fruit Hat Showgirl
- Giant Robot
- Girl Robot
- Girl Scout
- Harlem Globetrotter
- Headphones-Wearing Dragon - It is one of Twinkles' friends.
- Hoodie-Wearing Slug - It is one of Twinkles' friends.
- Humanoid Bear - It was said to have compatible kidneys alongside Beth's kidneys.
- Humanoid Catfish
- Humanoid Fox
- Humanoid Sun
- Humanoid Unicorn
- Japanese Businessman
- Kaiser Wilhelm II
- Lucky Cat
- Mel Gibson as William Wallace Look-A-Like - From the film Braveheart.
- Mexican Man
- Mr. Peanut Look-a-Like
- Mushroom Head
- Pink Balloon Animal
- Scottish Warrior
- Sea Captain in Rain Gear
- Small Cowboy on Dog
- Snake in Party Hat
- Snorkel Kid
- Space Monkey
- Sunglasses-Wearing Strawberry - It is one of Tinkles' friends.
- Sweatband-Wearing Star - It is one of Tinkles' friends.
- Trashcan-Wearing Creature
- Waka Flocka Flame Look-A-Like - He is one of Tinkles' friends.
- Winter-Wear Turtle - It is one of Tinkles' friends.
- Rick was the one that brought the parasites to the house, he can be seen picking up some rocks with some eggs at the end of "Mortynight Run" and can be seen binning the same rocks at the start of "Total Rickall."
- The parasites resemble the Rasklapanje, an enemy from Resident Evil 6
- Some of the parasites resembling humans from appearance to memories is based off the Worms from Kamen Rider Kabuto.