In classical antiquity, the Juvenalia, or Ludi Juvenales (Gr Ἱουβενάλια ὥσπερ τινὰ νεανισκεύματα), were scenic games instituted by Nero in C.E 59, at the age of 21, in commemoration of his shaving his beard for the first time, thus indicating that he had passed from youth into manhood. These games were not celebrated in the circus, but in a private theatre erected in a pleasure-ground (nemus), and consisted of every kind of theatrical performance, Greek and Roman plays, mimetic pieces, and the like.
The most distinguished persons in the state, old and young, male and female, were expected to take part in them. The emperor set the example by appearing in person on the stage; and Cassius Dio mentions a distinguished Roman matron, upwards of eighty years of age, who danced in the games. It was one of the offences given by Thrasea Paetus that he had not acquitted himself with credit at this festival (Cassius Dio, Roman History LXI.19; Tacitus, Annales, XIV.15, XV.33, XVI.21). Suetonius (Ner. 12) confounds this festival with the Quinquennalia, which was instituted in the following year, C.E 60.
The Juvenalia continued to be celebrated by subsequent emperors, but not on the same occasion. The name was given to those games which were exhibited by the emperors on the 1st of January in each year. They no longer consisted of scenic representations, but of chariot races and combats of wild beasts (Cassius Dio, Roman History, LXVII.14; Sidonius Apollinaris, Carm. XXIII.307, 428; Augustan History, "The Three Gordians", 4; cf. Lipsius, ad Tac. Ann. xiv.15).