Marvel Comics history
In the original Marvel Comics series, Straxus was governor of the Polyhex province of Cybertron, where he ruled with an iron fist from his Darkmount citadel. There, he operated a giant smelting pool where his Decepticons melted down captured Autobots or Empties (the derelict civilians of Cybertron) into molten metal, which was then used for manufacturing new Decepticons. Straxus, in addition to his axe, in cannon mode possesses more firepower than Megatron or Shockwave combined. Straxus is known to strike fear into even his own soldiers, once battering his own executive officer, the Insecticon Shrapnel, when he was in a bad mood. When a transmission from the Decepticons based on Earth reached Cybertron in the year 1985, Straxus ordered the capture of Autobot scientist Spanner so that he could construct a space bridge to act as a means of getting to Earth. When the Autobot spy Scrounge tried to locate Spanner, he ended up captured and brought before Straxus, who cut off Scrounge's recorder arm and sent him to the smelting pool. At the same time, Autobot communications officer Blaster, who was Scrounge's contact, also was captured, and nearly met his end in the pool before being saved by the Autobots Powerglide, Beachcomber, Warpath, Cosmos, and Seaspray, but not before the dying Scrounge gave Blaster the information he found. Straxus oversaw the completion and testing of the Space Bridge, and got angrier with each failed test. Meanwhile, an Autobot raiding party led by Blaster and Autobot scientist Perceptor planted and detonated explosives within Darkmount, destroying the citadel and sending Straxus into a great rage, as he went after their heads. When Blaster attempted to destroy the Bridge (which turned out to be Spanner, as he was turned into part of the bridge), Straxus fought him in a duel to the death. Though Straxus crippled Blaster with his axe, he was duped into accidentally cutting the bridge's fuel line, which destabilized the bridge's teleporting arch, which Straxus ended up falling into and being destroyed. The explosion also transported Blaster and his crew to Earth, where they would later meet up with the Earthbound Autobots.
Marvel UK stories
Details to come....
Transformers Collector's Club Fiction
In their "Shattered Glass" stories, it is revealed that the good version of Straxus is a poet. In the stories taking place in the universe of the "Wings of Honor" figures, he is one of the warlords who fought in the early days of the Cybertron civil war, who helped form a war council to counter the Autobot Elite Guard. He was one of that group who was killed by a well-placed bomb from one of Decepticon warlord Deathsaurus's troops, Falcon, as part of Deathsarus's plan of "eliminating the competition".
Transformers: United (2011)
Transformers Movie universe (2008)
In this continuity (expanded upon by the Transformers: Animated Allspark Almanac series of books), he is the Lord High Governor of the Decepticon colony Lucifer. He resembles his G1 counterpart.
Straxus gained his first-ever action figure in 2010 as part of the Transformers: Generations series, where his name was changed to "Darkmount" (as a homage to his base of operations) due to the Straxus name being unavailable at the time. His toy turns into a half-track self-propelled artillery truck inspired by the South African G6 Rhino vehicle, with a movable turret. He also possesses a tripod-mounted "howitzer" mode. In robot mode, his turret becomes his trademark axe, and he greatly resembles his G1 form. He also has "M-17" tampo-graphed on his vehicle mode as a homage to his first appearance in issue 17 of the Marvel Transformers series. His figure was originally supposed to have a gimmick with his howitzer mode where scout class figures could man him and use him as a weapon. The figure was repainted in 2011 as part of the Japanese version of Generations called Transformers: United, where he was given his original name and had much of the grey and red replaced with light and dark blue plastic. The entire figure would later be repainted with a new head as a new version of the Decepticon Pretender Skullgrin in 2011.