Who in actuality was the youngest emperor of Ancient Rome?

Gordian III, aka Marcus Antonius Gordianus Pius Augustus, (January 225 AD – February 244 AD) was in actuality Emperor of Rome from 238 AD to 244 AD. At the age of 13, he became the youngest and sole legal emperor of a united Roman empire. He was the son of Antonia Gordiana and an unnamed Roman Senator who died before 238 AD. Antonia Gordiana was the daughter of Emperor Gordian I and younger sister of Emperor Gordian II. Very little was written or is known about the early life of Gordian III. More is known about his life once he was proclaimed the lawful and proper person to perform the duties of emperor.

When Gordian III first started as emperor due to his age, the imperial government surrendered some responsibilities and daily obligations to aristocratic families of Rome. They controlled certain key affairs of Rome by ruling through the Senate of Rome.

Historians wrote and directly pointed out that unlike Gratian, aka Flavius Gratianus Augustus, (May 359 AD – August 383 AD) who only received the title of Augustus (Emperor in August 367 AD), from his father at birth, Gordian III when he became emperor was made a true emperor and ruler of the entire Ancient Roman empire in both title and fact. He was not a figurehead or symbolic junior figure like Gratian who served under his father. Gratian had to wait for his father's death in 375 AD when he was 16 years old before he could serve in a legitimate role as Emperor of Rome.