Karl Johann Felsko (Latvian: Kārlis Johans Felsko), (born 18 May 1844, Riga, Russian Empire — died 1918, Riga) was an architect and son of chief architect of Riga Johann Daniel Felsko. He was one of the leading architects during the building boom in Riga in the late 19th and early 20th century. There were more than 115 multi-story apartment and public buildings, factories and other buildings built following his designs. He was a master of Eclecticism style.