Hastings' Dictionary of the New Testament 
Otho is the name most often given to Marcus Saluius Otho, who, on becoming Emperor, was styled Imperator Marcus Otho Caesar Augustus. He was the younger son of Lucius Saluius Otho and Albia Terentia, and was born on 28th April, a.d. 32. From his earliest youth he was distinguished for effeminacy and profligacy, and became a boon-companion of the Emperor Nero. He married Poppaea Sabina, already the wife of Rufrius Crispinus, and mistress of Nero, in order, it is said, that Nero might find her easier of access. Under suspicion of continuing marital relations with her, Otho, who had already held the quaestorship, was given a legate’s post in Lusitania, where he remained from 59 to 68. The historians are unanimous that he was an excellent governor. When Galba in 68 revolted against Nero, Otho joined him and attended him to Rome, hoping, vainly as it transpired, that Galba would adopt him. Encouraged by an astrologer, who held out to him hopes of Empire, he plotted against Galba and brought about his murder (see under Galba). Both the army and the Senate hailed Otho as Emperor on 15th January, 69. In spite of the treatment Nero had meted out to him, he liked to be called Nero, and it may be that he was the more welcome to the populace by contrast with the severity of his predecessor Galba. He was elected one of the consuls for 69. But his reign was short. A new claimant to the Empire arose in the person of Vitellins (q.v.[Note: .v. quod vide, which see]
The Nuttall Encyclopedia 
Roman emperor, had been a companion of Nero; was created emperor by the Pretorian Guards in succession to Galba, but being defeated by the German legionaries, stabbed himself to death after a reign of three months (32-69).