Ugra is one of the Thousand names of God Viṣṇu (Vishnu) . Ugra means ‘full of terrible energy or power’. In Bhagavadgītā, the Viśvarūpa (Viswarupa)of God Viṣṇu has been described — Sañjaya (Sanjaya) compares its brightness to the rise of thousands of suns in the sky —
divi sūryasahasrasya bhaved yugapadutthita —
Arjuna has addressed this great and all-powerful form of God Viṣṇu as ‘Ugrarūpa’ (Ugrarupa). For this terrible and grand form, he is known as Ugra.
In Taittirīya Upaniṣad (Taittiriya Upanishad), it is said that the sun, the moon, planets and stars move in their path, as controlled by the Supreme God —
bhīṣodeti sūryaḥ.
Here, God’s rule or controlling power is called Ugra. God is called Ugra, because the stars and planets are ruled by him —
sūryādīnāmapi bhayahetutvāt ugraḥ (Śānkarabhāṣya)