Constantine I, also known as Constantine the Great, was a Roman emperor who ruled from 306 to 337 AD. He is recognized as one of the most important figures in Roman history, having been instrumental in the establishment and spread of Christianity throughout the Roman Empire. There are several synonyms which are often used when referring to Constantine I, including "the Great," "the First Christian Emperor," "the Founder of Constantinople," and "the Defender of the Faith." These terms help to capture the many accomplishments and achievements of this influential leader, who left an indelible mark on the history and culture of the Roman Empire.