Aparo died Tuesday at home after a short illness, said his daughter, Donna Aparo. He was 72.
Aparo, who grew up in New Britain, brought characters to life in his home studio in Southington, corresponding with DC Comics through the mail. He retired about four years ago, his daughter said.
Besides Batman and the Green Arrow, Aparo also did illustrations for Aquaman, the Brave and the Bold, Phantom Stranger and Spectre.
His big break came in the late 1960s when he was working for Charlton Press and his editor got a job at DC. The editor, Dick Giordano, brought Aparo with him to the comic book maker.
In a 2000 interview with Jim Amash for Comic Book Artist, Aparo said he went to Hartford Art School for a semester, but was mostly self-taught.
"I just drew as a kid and went with it," he said. "I studied and copied comic strips and comic books. I grew up with Superman, Batman, and Captain Marvel. I really liked Captain Marvel Jr. by Mac Raboy. That was beautiful stuff. I liked Alex Raymond, Milton Caniff ... all of those guys."
Aparo is survived by his wife, Julieann, and three children.