Per Wikipedia,
Ekadashi (Sanskrit: एकादशी, ekādaśī, "Eleven"), also spelled as Ekadasi, is the eleventh lunar day (Tithi) of the shukla (bright) or krishna (dark) paksha (fortnight) of every lunar month in the Hindu calendar (Panchang). In Hinduism and Jainism it is considered a spiritually beneficial day. Scriptures recommend observing an (ideally waterless) fast from sunrise on the day of Ekadashi to sunrise on the day following Ekadashi. Hindu scriptures teach that it is especially important to avoid all beans and all grains on this day because on the day of Ekadashi these two foods are contaminated by sin, one should eat only fruits and vegetables and milk products on this day .
Vedic (Lunar) and
Vaishnava Month
Presiding deity
Krishna paksha Ekadashi name
Shukla paksha Ekadashi name
Chaitra (चैत्र)
Vishnu
Papamochani Ekadashi
Kamada Ekadashi
Vaisakha (वैशाख )
Madhusudana
Varuthini Ekadashi
Mohini Ekadashi
Jyeshta (ज्येष्ठ)
Trivikrama
Apara Ekadashi
Nirjala Ekadashi
Ashaad (आषाढ)
Vaamana
Yogini Ekadashi
Shayani Ekadashi
Shraavana (श्रावण)
Sridhar
Kamika Ekadashi
Shravana Putrada Ekadashi
Bhadrapada (भाद्रपद)
Hrisikesha
Ananda Ekadashi
Parsva Ekadashi
Ashvin (अश्विन्)
Padmanabha
Indira Ekadashi
Paashunkushaa Ekadashi
Kartik (कार्तिक)
Damodara
Rama Ekadashi
Prabodhini Ekadashi
Margashirsha (Agrahayana)
(मार्गशीर्ष)
Keshava
Vaikunta Ekadashi
Mokshada Ekadashi
Pausha (पौष)
Naaraayana
Saphala Ekadashi
Pausha Putrada Ekadashi
Maagha (माघ)
Maadhava
Sat TilA Ekadashi
Bhaimi Ekadashi
Phalguna (फाल्गुन)
Govinda
Utpanna Ekadashi
Amalaki Ekadashi
Adhika month (अधिक)
Purushottama
Parama Ekadashi
Padmini Visuddha EkAdasii
Good Reads :
http://www.dlshq.org/religions/ekadasi.htm