Rahula

Also known as Rahula-gupta, Rahula-bhadra and Rahula-guhya-vajra (10/11th century).

An Indian Mahasiddha who was a teacher to both the great Atisha as well as the founder of the Shangpa Kagyu school, Khedrub Khyungpo Naljor. He is also known by the nickname of "the Yogin of the Black Mountain".

Another master by the same name is said to have given monastic ordination to the Mahasiddha Saraha. He cannot possibly be the same as the above mentioned one, as he must have lived much earlier.

Also, the name of the Buddha's son, which he fathered as Prince Siddharta, before he left his father's palace and eventually became Buddha Shakyamuni.