Ivan Drago Komelj (b. 7 January 1923 in Novo Mesto, d. 2 August 1985 in Ljubljana) was a Slovenian art historian, conservator, castle expert and documentalist. Following gymnasium education in his home town, he graduated in history of art from the Faculty of Arts in Ljubljana in 1949, where in 1965 he defended his doctoral thesis on gothic church architecture in Slovenia. Already during his student years he devoted his talents as both draftsman and organiser to the conservation of cultural heritage. In 1950, he was employed by the Institute for the Protection of Cultural Heritage, where he was responsible for the care of monuments located in the Dolenjska and Gorenjska regions and the Gorica part of the Primorska region, a job he was to hold for the rest of his life. He was known for his work as a con-servator and from 1975 also as head of the documentation centre, advisor to the director and mentor to younger colleagues working in regional institutes. He de-voted his research in particular to the Dolenjska region and performed pioneering research into medieval castle and church architecture and murals. He was the leading expert in historical monuments and facilitator of the erection of public monuments in Slovenia. He was also the founder in Slovenia of the discipline of castle studies. He led the renovation of monuments important at the national level (e.g. Kostanjevica Monastery, Branik Castle and Planina pri Rakeku Castle). Ivan Komelj and his colleagues prepared an overview of the cultural heritage entitled Cultural Monuments of Slovenia (White Book, 1974). At the time of the first integrated research projects and publications on gothic architecture, he was among the initiators of a series of guidebooks on the national monuments of Slovenia. He worked on a theory of cultural heritage protection, its inclusion in tourism and on history of conservation in Slovenia. He prepared topographies of the Dolenjska and Bela krajina regions and systematically collected old pictures and other material connected with monuments.