Akalo (also known as Archa Nine) is the 9th planet in the Arca System. It is an organic forest planet that is populated by the Akalouthians (a technological primitive people).
Andellor is a library planet for a highly evolved society.
Antilla is an ancient ringed planet which was the site of an early Autobot colonization effort. This colony was wiped out by the deadly plague known as Cosmic Rust as seen in The Transformers episode "Cosmic Rust."
Antilla is also home to adorable creatures known as Antillan Bumble-Puppies.
Aquatron was a planet introduced in the novel Transformers: Retribution notable for being almost entirely covered in water. It was part of the Quintesson Empire and its inhabitants were enslaved as part of the illusion of the Quintesson "Co-Prosperity Sphere." Aquatron was a Cybertronian colony, and its native inhabitants-the Aquatronians and the Sharkticons-are of Cybertronian descent. The Autobots and Decepticons arrive here and quickly learn that the planet is under Quintesson control, after one of the planet's artificial rings-used to gather and fire energy-disables both their ships. A massive battle then ensues between the Cybertronians and the Sharkticons, with the Sharkticons later abandoning the Quintessons in temporary favor of Megatron. However, the awakening of a massive Quintesson jellyfish known as the Hydratron-which while dormant had served as a continent/city for the inhabitants of the planet-proved devastating, and the Autobots and the Decepticons eventually left the planet behind. One benefit of their visit was that Aquatron was freed from Quintesson rule and fell to the jurisdiction of a massive race of underwater Transformers, including one known as Leviacon. The planet was also inhabited by the Pirahnacons, a deadly race that fed upon Transformers.