"Don, we've got Wildman penciling this series, but... can you give us redesigns for the main characters and we'll pay you later?"
Transformers: War Within: The Dark Ages is a six-part miniseries originally published by Dreamwave Productions in 2003, and set in the main G1 Dreamwave continuity. It centers on the arrival of The Fallen on Cybertron, and his plans to unleash an ancient evil that had been locked away below the planet's surface.
The series was written by Simon Furman and illustrated by Andrew Wildman, who had worked with Furman previously on the original Generation 1 Transformers series. Though most of the characters' redesigns were worked up by Don Figueroa, a few were done by Wildman himself, and the Fallen was designed by Pat Lee.
Set some time after The War Within, The Dark Ages sees the Autobots and Decepticons split into multiple factions following the loss of their leaders, Optimus Prime and Megatron. The destructive combiner teams are neutral by treaty agreement; and the conflict has simmered down to a low boil. Into this conflicted milieu comes the evil Fallen, who employs the Chaos Trinity to help him bring back an old friend, using the sparks of four genetically unique Transformers.
Notes
Like the original series, some of Don Figueroa's designs were later made into toys for the Titanium Series toy line, including The Fallen and Jetfire. Cliffjumper, a planned retool of Bumblebee (though their vehicle modes in the series were different), was displayed at BotCon 2006 as an unpainted prototype and will likely never see release.