Alejandro Montoya — aka El Águila — is an established Marvel Comics character who began his swashbuckling activities in "Powerman and Iron Fist" #58, way back in 1978. Montoya's first appearance saw him as a vigilante for underserved communities and a scourge to drug dealers and businesses that prey on the poor. Being the self-proclaimed Heroes for Hire, Luke Cage and Iron Fist were contractually obligated to bring Montoya to justice after he robs one of their clients — a careless, greedy property management company. Though the heroes begrudgingly defeated him initially, they allowed him to escape once the clock struck five — officially ending their business day.
While Montoya in "She Hulk" is insecure about being known as a matador, this may be a hint that he's also insecure about being labeled another M-word — mutant. In the comics, his "swashbuckling" persona is meant to detract attention from his obvious mutant powers, which he unfortunately lost during Marvel's "M-Day" event (via "New Avengers" #18). In the aftermath of the "Civil War," however, he was considered for possible membership in Tony Stark's U.S. Government-backed 50-States Initiative, which may mean his sword-fighting skills are learned rather than gifted.
It's currently unknown if El Águila will be more than an Easter egg in a singular episode, but it would certainly be fun to see him return in a more serious capacity.
