Maximinus I, also known as Maximinus Thrax and Caius Julius Verus Maximinus, was Roman emperor in AD 235-238.

He was conspicuous as the first barbarian who wore the imperial purple and the first never to set foot in Rome. He was the first of the so-called soldier-emperors of the 3rd century, but certainly not the last.

Born in about 173 in Thrace of a Gothicic father and an Alanicic mother, he was reportedly eight feet tall and of tremendous strength. He joined the army during the reign of Septimius Severus, but didn't rise to a powerful position until promoted by Alexander Severus. Maximinus was in command of the recruits from Pannonia, who were angered by Alexander's payments to the Alemanni and his avoidance of war. The troops elected the stern Maximinus killing Alexander and his mother at Mainz in 235. The Praetorian Guard elected him emperor, and their choice was grudgingly confirmed by the Senate, who were displeased to have a peasant as emperor.

Maximinus hated the nobility and was ruthless towards those he suspected of plotting against him. His suspicions may have been justified; two plots against Maximinus were foiled. The first was during a campaign across the Rhine, during which a group of officers, supported by influential senators, plotted the destruction of a bridge across the river, leaving Maximinus stranded on the other side. Afterwards they planned to elect senator Magnus emperor, however the plot was discovered and the conspirators executed. The second plot involved Mesopotamian archers who were loyal to Alexander. They planned to elevate Quartinus, but their leader Macedo changed sides and murdered Quartinus instead, although this was not enough to save his own life. Maximinus also reversed Alexander's policy of clemency towards the Christians, who were viewed as unsupportive enemies of the state.

His first campaign was against the Alemanni, who Maximinus defeated despite heavy Roman causulties in a swamp near what is today Baden-Württemberg. After the victory, Maximinus took the title Germanicus Maximus raised his son Maximus to the rank of Caesar and Prince of Youths. Securing the German frontier, at least for a while, Maximinus then fought the Dacians and the Sarmatians during the winter of 235-236.

Maximinus doubled the pay of soldiers, this along with continuous war, required higher taxes. The collection of taxes brought about a revolt in Mauritania, which for three months raised the two Gordians to the throne. A similar defection occurred in Rome, where the senators Pupienus and Balbinus were elected co-emperors. Maximinus marched on Rome, but at Aquileia Maximinus's troops, suffering from famine and disease, from a prolonged siege of the city became disaffected. Praetorian guards in his camp assassinated him, his son and his chief ministers. Their heads were cut off, placed on poles, and carried to Rome by cavalrymen. The Senate elected the 13 year-old grandson of Gordian I to emperor.

Preceded by:
Alexander Severus (222 - 235)
Roman emperors
Followed by:
Gordian I and Gordian II (238)