Brahmaraksasa

Brahmarakshasas (Sanskrit: ब्रह्मराक्षस) are fierce demon spirits in Hindu mythology.

Brahm Rakshas is actually the spirit of a Brahmin, a dead scholar of high birth, who has done evil things in his life or has misused his knowledge, who has to suffer as a Brahm Rakshas after his or her death. The earth-bound duties of such a scholar would be to disperse or impart knowledge to good students. If he did not do so, he would turn into a Brahma Rakshas after death which is a very fierce demonic spirit. The word Brahm means Brahmin and Rakshas, a demon. As per ancient Hindu texts they are powerful demon spirit, who have lot of powers and only few in this world can fight and over-come them or give them salvation from this form of life. It would still retain its high level of learning. But it would eat human beings. They have the knowledge of their past lives and vedas and puranas. In other words, they have qualities of both Brahmin and Rakshas.

It is said that the 7th century Sanskrit poet Mayurbhatta, who composed the noted Surya Sataka (one hundred verses in praise of Lord Surya) was troubled by Brahmarakshasha. He was doing penance at famous Deo Sun Temple located at Aurangabad district of Bihar. Brahmarakshas was living in the Peepal tree under which Mayurbhatta was doing penance and creating the verses. It was repeating the verses pronounced by Mayurbhatta, disturbing him. In order to defeat him Mayurbhatta started to pronounce words through nose. Since Brahmarakshasas or other spirits do not have a nose it was defeated and left the tree, which immediately turned dry. After the spirit left Mayurbhatta could peacefully create the hundred verses in praise of Surya, which cured him of leprosy.

...
Wikipedia