The U.S. government assigned Dr. Walter Newell, famed oceanographer, to supervise construction of an undersea city in the Atlantic Ocean. Unfortunately, it became a target of the Plunderer, and the city was rescued upon the arrival of Namor the Sub-Mariner. This was the first meeting between Newell and Namor, and the two became friends. However, their friendship was soon threatened when Newell was forced by the government to locate Namor, who was believed to be in league with an extraterrestrial threat to Earth. Creating the Stingray costume, Newell succeeded in capturing the Sub-Mariner, although Namor soon escaped and Newell, while initially defeating him a second time, allowed his friend to go. Stingray continued his friendship with the Sub-Mariner on many occasions. He helped Namor clear the Atlanteans’ name over the sinking of an ocean cruiser and exposed Attuma as the culprit, he spoke on Namor’s behalf in his attempts to gain official amnesty from the UN for past transgressions, and he later helped Namor locate his human father, Leonard McKenzie. However, McKenzie became the pawn of Tiger Shark and Llyra, and although Stingray helped Namor defeat his enemies, McKenzie was killed.
Newell is best known for his work as the chief caretaker of Hydrobase. Shortly after moving to Hydrobase, he married Diane Arliss, the sister of Tiger Shark. His oceanographical research consumed most of his time, although he had been known to don the Stingray costume occasionally, such as the time he helped the Thing, Triton, and Scarlet Witch defeat Roxxon Oil’s designs for the mystic Serpent Crown.
Stingray’s first association with the Avengers came when the team needed to use part of Hydrobase as an airbase for their Quinjets. Later, the Avengers needed to move their headquarters to Hydrobase at a time when their Park Avenue mansion was destroyed. During this time, Newell became part of the Avengers’ Ground Crew and, as Stingray, he even became an unofficial member of the group by participating in several missions, such as helping the team recover a nuclear sub from the eco-terrorist Peace Corpse. When Hydrobase was destroyed by the Lava Men, Newell was forced to continue his research privately.
More recently, Stingray joined the Avengers in helping re-organize their team after a long hiatus when most of their number were believed dead. He has also remained on hand to aid the Avengers on an as-needed basis, such as helping them against renegade Atlanteans and the Master of the World during the time the time-travelling Kang tried to conquer the Earth.
Sometime later he joined Captain America's Secret Avengers to act against the Civil War|Superhuman Registration Act. After Captain America was arrested Stingray accepted the offer of amnesty by Iron Man. He was then enrolled in the Initiative Training Program in the hope that he would become less reliant on his exoskeleton.