A typecast actor known for their macho action roles is cast in a movie where they play a tough guy Action Hero or macho guy type put in a position of responsibility for children. Sometimes this takes the form of a Badass and Child Duo. This usually results in in a Fish out of Water situation that is Played for Laughs as the macho manly man struggles to deal with new and unfamiliar problems that most family men would consider par for the course, such as dealing with a Potty Emergency, trying to cook meals, balancing work and family, and putting up with a Mouthy Kid. The macho man is forced to learn new skills, though he often finds creative ways to apply his action hero skills to a more domestic situation. Usually the children are bad or mischievous, and usually the "Action Hero" begins the movie "hating children" and gradually grows to love them over the course of the film.
To qualify as this trope, the casting is as important as the plot. A primary factor in Action-Hero Babysitter is to see the actor in an unusual (for them) and often humorous situation. The specific details of the character are often less important than just the fact that they are a badass or Action Hero, because that is what the actor invariably plays. This is similar to Playing Against Type, but instead of having the actor play someone unlike what they normally play, they play their regular character type but in an unusual situation. However, while the bulk of the movie will focus on domestic hijinks, there will often be at least a few action scenes, especially at the conclusion of the movie.
- The premise behind Beelzebub. So far there are four of them.
- In one filler episode Zoro from One Piece is forced to take care of some babies after being forcibly adopted into a family that takes in kids with no home.
- What Sanzo thinks he's become in the Burial arc of Saiyuki before he visits the three aspects and realizes Goku isn't just some little kid who was stuck in a cave.
- In Shōnen Onmyōji, Gurren, the most feared of Abe no Seimeis 12 familiars, is shown to have taken care of Masahiro when he was a child.
- Vathara's Walk Through the Valley has in Hiko one of the few serious examples and perhaps the only scientist among them. In addition to killing psi-actives who saw through Kenshin's mental camouflage, he cared for him during his transformation into a Little Bit Beastly kiryuu alterant, which entailed an iatrogenic coma.
- Kindergarten Cop with Arnold as a cop going undercover in a kindergarten. Hilarity Ensues.
- T-800 from Terminator 2: Judgment Day, also played by Arnold, has to protect the pre-teen John Connor.
- Also the T-800 from Terminator Genisys, which was sent back to 1973 to protect young Sarah Connor and was nicknamed "Pops".
- The Game Plan The Rock as a football player unexpectedly having to raise a ballerina daughter.
- The Cowboys with John Wayne has elements of this as his character is forced to learn how to deal with children he must use on a cattle drive ( but also somewhat subverts this trope when John Wayne's character is killed and the kids learn to kill in order to avenge his death and recover the stolen cattle).
- Mr Nanny, with Hulk Hogan as a former pro wrestler taking a job as a nanny/bodyguard to a couple of bratty kids.
- Pictured above: In The Pacifier, Vin Diesel plays a Navy SEAL tasked with babysitting the children of a dead scientist. Including two babies.
- Jackie Chan in The Spy Next Door. Unusually for the trope, Jackie already has a child-friendly Nice Guy image.
- The Babysitters Club: One of the baby sitters charges has been established from his first appearance as someone who hates all girls, including his own mother and sisters. But when the sitters decide to baby sit a bunch of kids together, they are stunned when the boy is very gentle and playful with the babies.
- The Rotten Tomatoes Show has a song called "Action Hero Babysitter".
- In an episode of Frasier, the macho Bulldog Briscoe proves himself to be a remarkably good, sensitive, babysitter to Alice Doyle. It isn't completely a cynical ploy to win her mother over: he really does seem to bond with Alice and take pleasure in doing so.
- In the first part of Fire Emblem: Genealogy of the Holy War, Finn was introduced as the disciple of Duke Quan. In the second part and in Fire Emblem: Thracia 776, he is the caretaker of Quan's son Leif and Lady Lachesis's daughter Nanna who, depending on the player's actions, can actually be Finn's biological daughter. Oifey and Shanan, who were respectively the Non-Action Guy and Tagalong Kid in the first part of Geneaology, have also become this by the time the second part begins.