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.

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:

• Marpa, the great translator and first native-born guru in Tibet who brought Buddhist teachings from India.
• Milarepa, Marpa's student . In Buddhist pictures and statues, Milarepa is shown with his right hand cupped against his ear. He does this to better listen to the teachings (dharma).
• Karmapa, the first consciously incarnating lama of Tibet.
• Gorakhnath
• Matsyendranath
• Nagarjuna
• Naropa
• Saraha
• Shantideva
• Tilopa

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

• Dowman, Keith (1986). Masters of Mahamudra: Songs and Histories of the Eighty-four Buddhist Siddhas. Albany, NY: State University of New York Press. ISBN 0-88706-160-5

• Murals of mahasiddhas in the Lukhang hidden temple
• Names of the 84 Mahasiddha (with brief explanation of their meaning).
• The Mahasiddha Linedrawings of H.R.Downs (in Dowman (1986)).
• MahaSiddha Dharma website