Mahasiddha

A mahasiddha (Sanskrit: "maha" - great, "siddha" - achiever) is type of yogi important in Tantra. They are found in both Hinduism and Tibetan Buddhism. They are connected with unusual ways of thinking and with the highest levels of spiritual enlightenment. They are very different from arhats, the saints who gave up the world to achieve buddhahood.
The Mahasiddhas are actual people who acquired magical powers from their spiritual practice. A mahasiddha is a bodhisattva, someone who can enter "nirvana" whenever they want, but instead choose to stay in "samsara" to help others.
In both Hindu and Tibetan Buddhist traditions there are 85 Mahasiddhas. The lists are not all the same, but there are many Mahasiddhas who appear on most lists. In Tibetan Buddhist art, they are often shown in paintings together, for example around the border of a "thanka".
Important Mahasiddhas.
Each Mahasiddha has come to be known for certain things. One of the most loved Mahasiddhas is Virupa, who is a saint of the Sakyapa sect. He lived in 9th century India and was known for his great attainments. Other important Mahasiddhas include:
Complete list of Mahasiddhas.
In Buddhism there are 89 Mahasiddhas: 
Acinta,
Ajogi,
Anangapa,
Aryadeva,
Babhaha,
Bhadrapa,
Bhandepa,
Bhiksanapa,
Bhusuku,
Camaripa,
Campaka,
Carbaripa,
Catrapa,
Caurangipa,
Celukapa,
Dan,
Darikapa,
Dengipa,
Dhahulipa,
Dharmapa,
Dhilipa,
Dhobipa,
Dhokaripa
Dombipa,
Dukhandi,
Ghantapa,
Gharbari,
Godhuripa,
Goraksa,
Indrabhuti,
Jalandhara,
Jayananda,
Jogipa,
Kalapa,
Kamparipa,
Kambala,
Kanakhala,
Kanhapa,
Kankana,
Kankaripa,
Kantalipa,
Kapalapa,
Khadgapa,
Kilakilapa,
Kirapalapa,
Kokilipa,
Kotalipa,
Kucipa,
Kukkuripa,
Kumbharipa,
Laksminkara,
Lilapa,
Lucikapa,
Luipa,
Mahipa,
Manibhadra,
Medhini,
Mekhala,
Mekopa,
Minapa,
Nagabodhi,
Nagarjuna,
Nalinapa,
Naropa,
Nirgunapa,
Pacaripa,
Pankajapa,
Putalipa,
Rahula,
Saraha,
Sakara,
Samudra,
Santipa,
Sarvabhaksa,
Savaripa,
Syalipa,
Tantepa,
Tantipa,
Thaganapa,
Tilopa,
Udhilipa,
Upanaha,
Vinapa,
Virupa,
Vyalipa,
Lokesh