Superman as Nightwing
The Prussian blue color of Superman's Nightwing costume is reminiscent of the plumage of the nightwing, a Kandorian bird. Superman and Jimmy Olsen first adopt their Nightwing and Flamebird identities during an adventure in Kandor in January 1963 (S No. 158: "Superman in Kandor" pts. I-III; "Invasion of the Mystery Super-Men!"; "The Dynamic Duo of Kandor!"; "The City of Super-People!"). They employ them again during a second adventure, in August 1964 (WF No. 143: "The Feud Between Batman and Superman!" pts. I-II -- no title; "The Manhunters from Earth!"). (TGSB)
Van-Zee as Nightwing
Dick Grayson as Nightwing
Later still, Dick Grayson, the original boy wonder Robin, takes the name—but not the costume—of Nightwing as his new heroic identity (Tales of the Teen Titans No. 44, Jul 1984: "There Shall Come a Titan!").