While Frieza is one of Dragon Ball's most prominent, fearsome villains, one who's has gone from interstellar tyrant to unlikely ally and back again over the course of Akira Toriyama's shonen franchise, the extraterrestrial enemy was never alone -- he had a family the whole time.
Making his debut in the 1991 anime film Dragon Ball Z: Cooler's Revenge, which hits its 30th anniversary this year, was Frieza's older brother, Cooler. Cooler was the first movie villain Goku faced as a full-fledged Super Saiyan and would go on to become the first villain that Goku and the Z Fighters confronted in more than one film, introduced two years before Broly's debut. And while Cooler's place in the official Dragon Ball canon is still up for debate, the film remains a thrilling story even three decades after its premiere in Japan.
Directed by Mitsuo Hashimoto, Cooler's Revenge opens with the revelation that Frieza has an estranged older brother who is preoccupied with terrorizing a different part of the galaxy. This is made evident with Cooler refusing to step in and help Frieza eradicate the Saiyans, inadvertently resulting in Goku making his way safely to Earth as a baby. Decades later, Cooler learns a Super Saiyan from Earth killed his younger brother and travels to the planet to avenge him, encountering Goku and the Z Fighters as they enjoy a camping trip only to witness the unleashed power of a Super Saiyan firsthand.
One of the most striking things about Cooler's Revenge is that Goku is sidelined for much of the film, after being blindsided in the beginning from an attack by Cooler himself. This leaves the bulk of the battles on Gohan, Krillin and Piccolo as they scramble to stay one step ahead of Cooler's henchmen before Cooler himself decides to join in. While everyone rightfully remembers the film for the climactic fight between Goku and Cooler's unique final form, Cooler's Revenge is really a showcase for Piccolo, with the Namekian warrior revealing just how powerful he has become since fusing with Nail on Namek.
Cooler's Revenge was so successful that the next Dragon Ball Z film, released eight months later in March 1992, was a direct sequel in Dragon Ball Z: The Return of Cooler, with the villain resurrected in a powerful, metallic form as he menaced New Namek. Though the canon status of Cooler's Revenge has never been confirmed -- with Frieza and his father King Cold never acknowledging Cooler's existence in the main anime series -- the events of the film don't directly contradict the anime's story, and it's presumably set during the three-year training period before the Androids' arrival. Cooler himself would make non-canonical appearances in the OVA Dragon Ball: Plan to Eradicate the Saiyans, Super Dragon Ball Heroes, Dragon Ball GT and a whole slew of video games.
While Frieza has enjoyed resurrection and his own spurned attempt at redemption over the course of Dragon Ball Super, Cooler remains noticeably absent from the franchise, further underscoring the possibility that Cooler's Revenge is quietly not part of the official canon. Regardless of its place in continuity, Cooler's Revenge is a leaner, faster DBZ film and all the better for it, giving Goku one of his more memorable cinematic opponents while further building the menace of Frieza and his family. Giving Goku his first major test after achieving the Super Saiyan transformation, Cooler's Revenge is still a fan favorite 30-years later for a good reason.