Nyala Pema Dündul

Nyala Pema Dündul (1816–1872), also known as Terton Nyala Pema Duddul, was a teacher of Dzogchen and Tantric Buddhism in Eastern Tibet.
In particular, he discovered and practiced the terma of the long-life practice of Guru Amitayus, called the Union of Primordial Essences.
Most sources state that the teacher in 1872 attained rainbow body. According to one source, he on purpose did not, but reduced the left dead body in size and transformed it so that it would not decompose. According to the source the small body is now hidden at a secret location.
Many of his students attained rainbow body (e.g. Ayu Khandro and Nyala Rinpoche Rigdzin Changchub Dorje).