Fortress Maximus is a character introduced in Season 4 of The Transformers.
- French name (Canada): Forteresse Maximus
- Russian dub name: Крепыш Максимус ("Krepish Maximus", Fortress Maximus)
When the Hive of Nebulos had developed the massive Transformer Scorponok in 2007, Spike found that his only available resources to combat the threat were the Hive's older technology and the pacifist Autobot Cerebros. Spike used the technology to create an Autobot giant, at the same time re-engineering Cerebros to become the new robot's head, and to take Spike himself as his own head (Cerebros seemed to get little say in these matters). The giant, named Fortress Maximus, blasted off for Cybertron, where he expectedly fought (and won) against Scorponok. After Maximus/Cerebros and Spike saved Cybertron and Earth from the Hive and the Decepticons, Optimus Prime sent them back to Nebulos as its guardians.
- At 22" (56 cm), the G1 Fortress Maximus toy (and therefore is repaints) is the third the tallest Transformer toy ever produced by far until the release of the 24" Generations Metroplex. Another Fortress Maximus, specifically Titans Return Fortress Maximus, won back the title. However the G1 toy is still the heaviest.
- 'Fortress Maximus' was likely a considered name for the character that eventually became Metroplex in Generation One. The Marvel comic adaptation of the 1986 Movie even refers to Autobot City as Fortress Maximus in a caption.
- Fortress Maximus was the first toy to be released with a bona-fide Earthling figure. All of the other Headmasters' companions were from Nebulos. (Although Maximus's on-package bio refers to 'the Nebulan leader, Spike', the general consensus is that it was supposed to be the popular figure from TV and other media, who is almost certainly an Earthling.)
- When Spike transforms to join Fortress Maximus for the last time in the Generation 2 book, Cerebros is not shown, and Spike transforms directly into Fortress Maximus's head. Maximus is shown to be no larger than Megatron. In real-life terms, it's an obvious series of art errors; in the context of the story, one might wonder if Maximus was reduced back to his original, smaller, size. It seems improbable, considering that Spike had been retired for years by that point.
- Fortress Maximus has the distinction of having one of the most well known Transformers bootleg versions in existence. While Cerebros has been omitted, the Spike figure is the same, and the body has been scaled down to match, effectively making the body compatible with any other Headmaster head. It also fetches absurd prices for a bootleg.
- In The Transformers cartoon, it is unclear if Fortress Maximus had any sentience of his own; he did speak once in his own voice. But for the most part, even Cerebros' will seemed to be pushed aside so Spike could run the whole thing himself.