Hasmukhray Vrajlal Yajnik (12 February 1938 ― 10 December 2020), better known as Hasu Yajnik, also spelled Hasu Yagnik was a Gujarati writer and editor. He wrote novels, short stories, criticism, folklore, and children's stories. He was a professor of Gujarati in many government colleges in Gujarat.
He wrote twenty novels, three short story collections, two jail stories, four medieval stories, and criticism of four medieval works. He edited twelve folk works and six works of children's literature.
He was the registrar of the Gujarat Sahitya Akademi, Gandhinagar from 1982 to 1996. He was a founder and managing trustee of the Meghani Lokvidya Sanshodhan Bhavan, Ahmedabad from 1996 to 2005.
He died on 10 December 2020 due to COVID-19 in Ahmedabad at the age of 82.