Constantius I (Flavius Valerius Constantius Chlorus) "the Pale", Emperor of Rome
Governor of Dalmatia, appointed Caesar to rule Gaul and Britain March 1, 293. He was the son of *Eutropious, a Dardanian nobleman descended from the *Gordiani, and his wife, *Claudia, daughter of *Claudius II (Marcus Aurelius Flavius Claudius Gothicus), a virtuous and worthy Roman Emperor (268-270), who was a soldier, statesman, and a distinguished officer. Born in Illyria 214, he was trained in the hard school of warfare on the Danube frontier, and died of the Plague in 270, aged 55, whereupon his brother Marcus Aurelius Claudius Quintillus became Emperor. Constantius I became Emperor of Rome in May 305, and in right of his wife, King of England. He was born in 242 and died at Eboracum (present day York, England) on July 25, 306. On becoming "Caesar," he was required by Diocletian to put aside *Helena and to take Maximian's stepdaughter, Theodora, as his wife. From the first union, *Helena and *Constantius I had an illegitimate son, *Constantine the Great. He married (2) Theodora, daughter of Maximinus, Roman Emperor.
Gibbon says *Claudia was the niece of *Claudius II (Marcus Aurelius Flavius Claudius Gothicus).
Encyclopedia Brittanica maintains Constantius I's descent from Claudius Gothicus was a fiction.