The Amazing Spider-Man #245 (1983)
Writer: Roger Stern
Artist: John Romita Jr.
While trying to find Lefty Donovan, Spider-Man is called out by the Hobgoblin. They fight for a while. Spider-Man takes off Hobgoblin’s mask and it’s Lefty. Lefty spouts something about his boss, and it turns out that the real Hobgoblin just wanted to see the effects of Osborn’s strength enhancing formula before testing them himself. Lefty dies from the glider he’s on crashing into a building via remote control by the real Hobgoblin.