By David Ng, Los Angeles Times Staff Writer Superhero fans and opera buffs seem to exist in two separate universes. But their rarefied worlds collide over the rainbow bridge of Richard Wagner's "Ring" cycle. The four-opera epic, which is getting its full-length L.A. debut at the Dorothy Chandler Pavilion in late May, has inspired (both directly and indirectly) the creation of several key superheroes from page and screen. Here are some of the modern-day heroes who owe their existences, at least in part, to Wagner's 19th century tetralogy. Marvel's Valkyrie, above, is loosely based on Brunnhilde, the winged female-warrior protagonist of Wagner's "Ring." The Marvel incarnation has assumed several forms over the years in a number of different series, including "The Avengers," "The Defenders," "The Incredible Hulk" and "The Order."TM and © 2010 Marvel Characters Inc.