Year 124 (CXXIV) was a leap year starting on Friday of the Julian calendar. At the time, it was known as the Year of the Consulship of Glabrio and Flaccus (or, less frequently, year 877 Ab urbe condita). The denomination 124 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

• January 1 – Gaius Bellicius Torquatus and Manius Acilius Glabrio begin the year as the new consuls, but the two are replaced in April.
• May – Aulus Larcius Macedo, the former Governor of Galatia; and Publius Ducenius Verres take office for four month as the suffect consuls to succeed Bellicius and Glabrio, and serve until the end of August.
• September – Gaius Valerius Severus and Gaius Julius Gallus replace consuls Larcius and Ducenius and serve until the end of the year.
• Emperor Hadrian begins to rebuild the Olympeion in Athens.
• Antinous becomes Hadrian's beloved companion on his journeys through the Roman Empire.
• During a voyage to Greece, Hadrian is initiated in the ancient rites known as the Eleusinian Mysteries.

• In northern India, Nahapana, ruler of the Scythians, is defeated and dies in battle while fighting against King Gautamiputra Satakarni. This defeat destroys the Scythian dynasty of the Western Kshatrapas.

• Apuleius, Numidian novelist, writer, public speaker (approximate date)^[1]

• Marcus Annius Verus, father of Marcus Aurelius
• Nahapana, ruler of the Scythians (approximate date)
• Sixtus I, bishop of Rome according to Roman Catholic tradition (possible date)^[2]