Aruja was one of the warriors belonging to the army of Rāvaṇa (Ravana), king of Laṅkā (Lanka). He, along with other warriors, launched an attack on Rāmacandra (Ramachandra).

Mahābhārata (Kinjawadekar)(3.285.2)
Mahābhārata Vols. 1-43 (Siddhāntabāgīśa)(3.239.2)