Marvel Animation Studios has debuted three photos from Iron Man & Hulk: Heroes United, the upcoming animated adventure that debuts on Blu-ray and DVD April 23, 2013. Adrian Pasdar and Fred Tatasciore voice the title characters, who team up to defeat the nefarious Zzzax, a creature who can absorb human minds. Take a look at these photos, then read on to see what Marvel's Jeph Loeb had to say about this stand-alone movie.

Zzzax first appeared in a 1973 issue of the Incredible Hulk comic book. This new movie will give fans his origin story, with Dee Bradley Baker (American Dad!) voicing the villain. Here's what Jeph Loeb had to say about the story.

"We see his origin in the movie. It's what would happen if the entire Eastern seaboard [electrical grid] went out. The two heroes meet up, thinking of each other as to blame. Calamity ensues."

While this is not being made as a sequel to Marvel's The Avengers, Jeph Loeb revealed it will feature the same tone.

"We welcome people to interpret any way they like. In tone and character, we want to follow our best leader. The challenge was to pick up the banter between the two of them. Certainly, Adrian Pasdar's performance is inspired by what Robert Downey Jr. does, and Mark laid down such an incredible path for us to be able to follow."

The Marvel executive also revealed he hopes this leads to more animated adventures that go straight to Blu-ray and DVD.

"It's our hope that we will start doing more feature-length direct to Blu-ray and DVD stories. They'll more than likely be in team-up situations. We find it works really well when we have big exciting adventures with two or more of our heroes."