Devadatta

Devadatta (Sanskrit and Pali: देवदत्त devadatta; Sinhalese: දේවදත්ත; Burmese: ေဒဝဒတ္) was by tradition a Buddhist monk, cousin and brother-in-law of Gautama Siddārtha, the Śākyamuni Buddha, and brother of Ānanda, a principal student of the Buddha. Devadatta was a Koliyan and is said to have parted from the Buddha's following with 500 other monks to form their own Sangha, most of whom are said to have been Shakya clan relatives of both Devadatta and Siddhartha.

Read more about Devadatta:  Etymology