The Knoller C.I was a reconnaissance aircraft built in Austria-Hungary during World War I for use by the Austro-Hungarian army. It was a conventional biplane design with staggered wings, and seated the pilot and observer in tandem in an open cockpit. The upper wing was swept back.
Production was undertaken at Phönix, but it was built only in small numbers before being supplanted by the Knoller C.II and not all of the examples built were actually flown, with most being placed in storage without engines.