Upakṛṣṇa (Upakrishna) is one of the follower-warriors of Skanda-Kārtikeya(Kartikeya). He assisted Kārtikeya (Kartikeya) while slaying Tārakāsura(Tarakasura).

Mahābhārata (Kinjawadekar)(9.45.57)
Mahābhārata Vols. 1-43 (Siddhāntabāgīśa)(9.45.57, see footnote, vol. 29, p. 476)