Eugen Viktor Feller (26 January 1871 – 15 November 1936) was a Croatian pharmacist, entrepreneur and pioneer of the industrial drug production in Croatia. Feller was born in 1871, in Lwów region, which after the partition of Poland was at the time a part of Austro-Hungary province known as Kingdom of Galicia and Lodomeria, to a Jewish family of David and Elizabeta (née Holzer) Feller. He was married to Ida (née Oehmichen) Feller, with whom he had twelve children, among them William Feller. In the late 19th century, Feller achieved fame with the elixir "Elsa Fluid" (named after his mother nickname, Elsa), whose production along with other cosmetic preparations took place in Donja Stubica. In Donja Stubica, Feller built the pharmaceutical factory, laboratory, and family house with pharmacy.