Aliens are creatures who comes from other planets. Almost all the aliens in this series are aliens who come from the Ata Ta Tiga Planet.
Main in series
- Adu Du: Adu Du is 20 alien years, he's a green colored alien. He has appeared since Season 1, Episode 1.
- Probe: Adu Du's evil robot sidekick. He has appeared since Season 1, Episode 1 too.
- Bago Go: He is the Dealer of Illegal weapons of Ata Ta Tiga. He is also fond in cheating about the price of his weapons to his buyers. He has appeared since Season 1, Episode 10.
- Ejo Jo: A evil alien. He wears a Red Combat Armor Suit, he has 2 colored red of lines below in his eyes. His eyes are colored red.
- Fang: Fang was recognised as a normal human school student before, since Season 2, Episode 1 but it was until his true identity as an alien was revealed in Season 3, Episode 24.
- Captain Kaizo: Captain Kaizo is a new character of the series and made his debut on Season 3, Episode 20. He is Fang's older brother. His true identity as an alien was revealed in Season 3, Episode 24.
- Lieutenant Lahap: He is shown to be Captain Kaizo's sidekick in his first debut on Season 3, Episode 24.
- Tengkotak: A alien group that make it's first appearance in BoBoiBoy: The Movie.
- Bora Ra: Bora Ra is an alien from Ata Ta Tiga planet. Bora Ra is the leader of The Tengkotak alien group. He makes his debut in BoBoiBoy: The Movie and appears in a flashback in BoBoiBoy Galaxy.
- Gaga Naz: Gaga Naz is a alien from Ata Ta Tiga planet. Gaga Naz is a member of The Tengkotak alien group. He made his debut in BoBoiBoy: The Movie.
- Yoyo Oo: Yoyo Oo is an alien from Ata Ta Tiga planet. He is one of the members of the notorious Tengkotak group. He made his debut in BoBoiBoy: The Movie.
- Kiki Ta: Kiki Ta is an alien from Ata Ta Tiga planet. She is one of members of the Tengkotak group. She plays the role of a pilot on the Tengkotak spaceship as well as a sniper. She made his debut in BoBoiBoy: The Movie.
- Cici Ko: Cici Ko is the character in BoBoiBoy: The Movie. He is one of members of the Tengkotak group. His role is a janitor. He returns in BoBoiBoy Galaxy as commander of team TAPOPS.
- Captain Separo: Captain Separo is a leader of the Space Pirates. He made his debut in first episode of BoBoiBoy Galaxy.
- Cattus: A cat-like alien that BoBoiBoy's Gang found in Planet Gurunda.
- Female Computer: Adu Du's computer. Mostly used to gain information about BoBoiBoy and his friends.
- Male Computer: Ejo Jo's computer. Same as Adu Du's computer, but this one more modern looking and can gain more and actual information.
- Waibi : A cactus-like humanoid alien, a hunter from Gurunda Planet and along with his family live in Kaktoi Tribe
- Unlike most alien, Fang and Captain Kaizo appearance is more look-like a human. However, it is unknown if its their false-form or its already their true-form.