Story

Jaco is a self-styled "super elite" member of the Galactic Patrol, an organization that upholds peace and justice throughout the universe.
He's also an old friend of Bulma's, first making her acquaintance during his primary position as the man in charge of watching over Planet Earth and its surrounding areas.

During the film, he comes to Earth in order to warn Bulma that the wicked Emperor Frieza has been resurrected and is traveling toward the planet.
Upon being told that the one who defeated Frieza in the past, Goku, is off training with God of Destruction Beerus, Jaco scoffs that such a thing couldn't be possible as he believes that Beerus doesn't actually exist!

Bulma had never actually seen Frieza in person at that point, so Jaco draws her a picture that vaguely resembles him while he explains the situation at hand.
Initially he intends to merely drop Bulma off at the site where Frieza is touching down, but in the end she manages to convince him to join the fight.

Jaco puts on an impressive display in the battle against the Frieza Force alongside Gohan, Krillin and the others, but when it comes time to face Frieza himself, Jaco backs down, saying, "I've already done more than enough in this fight. My superiors would never expect me to challenge the Evil Emperor himself!"

When Jaco witnesses Goku return to Earth and go toe-to-toe against Frieza, Bulma informs him that he's not an Earthling but a Saiyan. Jaco is shocked, saying, "You're obviously joking. The Saiyans were a brutal warrior race driven to extinction. There can't be one here."
However, he soon comes around to the truth but decides to keep it to himself and says, "I'll pretend I didn't hear that. It was my job to keep this world Saiyan-free. That would be way too much paperwork."

Jaco also has a bit of a fan moment upon seeing Lord Beerus for the first time, asking Bulma, " Do you think you can get a quick picture of me next to him?" but he decides against it after she replies, "You're more than welcome to ask him yourself, Jaco, but don't blame me if the guy disintegrates you."

First Appearance

Dragon Ball Z: Resurrection 'F'

Trivia

Jaco is the star of his own Dragon Ball prequel manga called Jaco the Galactic Patrolman!

In the prequel manga, Jaco comes to Planet Earth as part of his duties in the Galactic Patrol.
There, he meets Bulma's older sister, Tights, and even has infant wunderkind Bulma repair his damaged spaceship!

(From "Jaco the Galactic Patrolman")

→Preview: Next week's character is someone who fights for peace just like Jaco!