Shimon or Simeon ben Hillel was the son of Hillel the Elder. Little is known about him. Simeon was the father of Gamaliel I, and grandfather of Simeon ben Gamaliel.A history of the Mishnaic law of Holy Things: Volume 2 - Page 199 Jacob Neusner - 1978 "... had been received by him from "Miyyasha who had received it from Abba, who had received it from Shammai and Hillel, the last Zug." But Rabban Gamaliel I was the grandson, perhaps the son, of Hillel, whom he had ..."
Rabbinical tradition considers him Nasi of the Sanhedrin, in succession to his father.Shabbat 15a, Sefaria
Some Christian writers identify him with the Simeon who blessed the infant Jesus.
References