Marvel's Agents of S.H.I.E.L.D. won't be airing tomorrow, but a one-hour special that offers up a sneak peek at Joss Whedon's Avengers: Age of Ultron will play instead.  Kevin Feige recently commented on both the superhero sequel's title villain, and what fans can expect to see in tomorrow's special.  We've also got a clip from the promotional spot that highlights Marvel Studio's 2008 films The Incredible Hulk and Iron Man, two big gambles that have paid off quite well in recent years.

Marvel Studios: Assembling a Universe will premiere Tuesday, March 18th at 8:00pm on ABC.  Hit the jump for Feige's comments and a peek at the special.

Here's what Feige had to say about Ultron, played by James Spader in Avengers: Age of Ultron (via Movies.com):

"Introducing the new characters is going to be a lot of fun for the movie," said Feige. "That ever-changing roster is very important in the Avengers comics, and so how do we start to play with that [on the big screen]? Also our bad guy is great. I think people are going to be very, very excited to see what we're doing with the voice that Joss [Whedon] is bringing to life with James Spader for Ultron. We love Ultron from the comics, and have always loved Ultron, and at no point do we want him to just be a robot. We want him to have an extreme personality and attitude, and James Spader is doing an unbelievable job. Again, for us it's always about subverting expectations. Whenever you think you know what's coming next, we surprise people or deliver it in a slightly unexpected way. And Spader is doing that with Mr. Ultron."

Feige also teased fans with what they could expect to see in tomorrow night's special:

"They're advertising it as a first look, and that is an honest statement," he told us. "We don't start filming for another week and a half, so you're not going to have a lot of first-unit footage because it doesn't exist yet. But you certainly get more than just a peek at some of the new fun things we have in store."

Watch a clip from the aforementioned special below: