Fortress Maximus/Primax 785.06 Alpha

Fortress Maximus is a City-bot introduced in The Headmasters anime. He is formed from the city/spaceship Battleship Maximus, which is the Transector, and its captain Fortress, who is the Headmaster. Fortress himself is formed from the non-sentient communications room of Battleship Maximus, the intermediate Transector, and the human-sized Cybertronian Cerebros, Fortress Maxiumus' smallest Headmaster component. Ever since the development of the Headmaster technology, Cerebros almost always appears and gets referred to as Fortress.

4 Million Years Ago
During the Great War, Fortress was among the Cybertronians who led refugees off Cybertron to get away from the fighting. Fortress' group of refugees eventually reached the Planet Master. To better survive the harsh climate, they built larger bodies for themselves. They could then transform to become the heads of these more powerful forms.

While on Planet Master, a time-traveling spaceship/base called Brave Maximus landed there, this would later inspire the creation of Fortress' city/ship Battleship Maximus which could transform into a Transector he could combine with to form Fortress Maximus.

2011
The inhabitants of Planet Master themselves eventually split off factions, some claiming loyalty to the Destrons, while others held loyalty to the Cybertrons, though neither group came into direct contact with Seibertron (or Earth) until 2011.

Upon meeting again with the Cybertrons of Seibertron, Fortress quickly became a lead figure not only to his own troops, but to most of the other Cybertrons in the ongoing war, though he loyally answered to Rodimus Convoy. Primarily, he led the other Headmasters into battle, often working away from the other Cybertrons and handling overly dangerous situations.

When Seibertron was destroyed, Rodimus Convoy vowed to search the universe for a new home for the Transformers. He transferred the title of Supreme Commander to Fortress, but he kept the Matrix of Leadership (presumably as a reminder that it was a temporary).

Fortress wasn't entirely confident that he was the best choice to simultaneously hold the rank of Captain and Supreme Commander, not because of any discomfort or indecision performing the duties, but due to a certain common tendency to feel like he wasn't worthy. Nevertheless, he led the Cybertrons against Galvatron and Scorponok decisively and was popular as a leader. While some of the other Headmasters had trouble getting along with humans, Fortress proved himself reasonably friendly, or at least good at making silly faces to amuse children (and talking them into dangerous missions). Fortunately, Arcee was around to help smooth relations on both sides, as well as to help Fortress personally to coordinate and present plans.

In Scorponok's final campaign against the Cybertrons, Fortress Maximus battled his arch enemy, and thanks in part to Sixshot's intervention, the work of the Cybertrons as a team, and all the present Cybertrons troops—along with Daniel Witwicky—lending him their energy and the power of friendship via a Head Formation, he was able to overcome and destroy Scorponok's Transtector, as well as his plan to destroy the Earth, sending the Destrons into retreat once and for all.

Fortress continued to lead the Cybertrons as they left Earth for good to travel around the galaxy, trying to repair all the damages dealt in the war and to remain vigilant should the Destrons return.

Super-God Masterforce
Fortress was seen briefly trying to relay a message to the Cybertron Pretenders through great interference.