Hemendra Kumar Roy (Bangla: হেমেন্দ্রকুমার রায়) was a Bangali writer noted for his contribution to the early development of the genre of children's literature in the language. He was a noted contributor to the early development of Bengali detective fiction with his 'Jayanta-Manik'-stories, dealing with the exploits of Jayanta, his assistant Manik, and police inspector Sunderbabu. Roy also translated the Rubaiyat of Omar Khayyám into Bengali. One of the best translations anywhere of Alice in Wonderland is Roy's Ajab Deshe Amala.

He is best remembered as the creator of Bimal-Kumar, the adventurer duo and Jayanta-Manik the detective duo. It was Bimal-Kumar's adventure story Jokher Dhan, for which he is famous in Bengali literature for children. He was a staunch believer in supernaturals and he used the supernatural element in several of his adventure and mystery stories. He was also a painter and the choreographer for Shishirkumar Bhaduri's Seeta. He created a comic series titled Tara Teen Bondhu, which consists of seven short stories such as 'Kukur Kahini', 'Nakuler Daon Mara', 'Maharaja Chor Churamoni Bahadur', 'Kamon Kore Totlami Sare', 'Kartik Pujor Bhoot', 'Der Dozon Jahagi', and 'Madhureno Somapoyet'. The three main character of this series, Atal, Patol and Nakul, won huge popularity among the children and youngsters.

Pinaki Roy, who has offered post-colonial interpretations of Bengali detective fiction, gives primacy to Roy more as a writer of sleuth narratives than of children's literature. Pinaki Roy credits the litterateur for initiating a trend which would ultimately bring Bengali detective-story-writing from its colonial phase to its anti-imperialistic one: "Jayanta, the detective-cum-scientist, is probably one of the earlier fictional Indian sleuths who use their Indian sensibilities to capture Indian criminals operating in what could be idenfied as an 'indigenous' atmosphere.