Kilby Island (66°16′S110°31′E) is a rocky Antarctic island, 0.2 mi (0.32 km) long, lying northeast of McMullin Island in the entrance of Newcomb Bay, in the Windmill Islands. It was first mapped from air photos taken by USN Operation Highjump and Operation Windmill in 1947 and 1948. It was named by the US-ACAN for Arthur L.