ATTALUS ăt’ ə ləs (̓Άτταλος, meaning unknown). King of Pergamum.

The Attalus to whom the Romans wrote commending the Jews (1 Macc 15:22) was prob. Attalus II Philadelphus who reigned from 159 to 138 b.c., for there seems to be no good reason for doubting that the Rom. decree belongs to 139 b.c. rather than a cent. later, as implied by Jos. Antiq. 14. 8. 5 (see HJP I. 1. 266f.).

Like his father Attalus I and brother Eumenes II, he was a close ally of Rome. He was an able ruler and strengthened his kingdom by founding cities (e.g. Attalia) as well as by warfare and diplomacy. His nephew, who succeeded him, bequeathed the kingdom of Pergamum to Rome.

When in 153 b.c. Alexander Balas claimed the Syrian throne from Demetrius I and thereby established Jonathan as Jewish high priest (1 Macc 10), he was actively supported by Attalus.

International Standard Bible Encyclopedia (1915)

at’-a-lus: King of Pergamum, mentioned in 1 Macc 15:22 among the kings to whom was sent an edict (Ant., XIV, viii, 5) from Rome forbidding the persecution of the Jews. See Attalia.