It is no accident one of the world's biggest movie stars, Robert Downey Jr., maintains that notation after his name. The "Iron Man" star is, of course his father's namesake. But fans may not know that the "Sr." Downey is a noted indie filmmaker. Once filming began on "Iron Man 2," the iconic director, Downey Jr. said, was never far from his mind.

"Well, sure, any time your dad is revered," the 45-year-old actor told MTV News. "I mean, I grew up with people saying, 'Hey, that's Bob Downey's kid' -- and understandably so."

The actor's father has a backstory worthy of the big screen: He served in the Army, played minor-league baseball (striking out Yogi Berra in a game), held the title of Golden Gloves boxing champion and was working as an off-Broadway playwright by age 22. In the 1960s, he made a name for himself writing and directing experimental films like "Balls Bluff" and "No More Excuses," but it was the brilliant 1969 advertising spoof "Putney Swope" (Robert Jr. was 4) that really put him on the map. Thirty years later, he would direct his son in "Hugo Pool," his last wide-release film.

"He was a great innovator and a heck of a filmmaker," Downey said of his dad, now 73.

In the "Iron Man" follow-up, Downey's Tony Stark is similarly grappling with the memory of his father, a respected weapons manufacturer who left his son with vast wealth, power and lots of unanswered questions. "In Tony's case, it's really this massive looming shadow of his dad's posthumous perfection," Downey said of the plot. "That's a tough thing for him to live up to.

"The big idea, the theme, was legacy -- a double legacy," he continued. "There's the legacy that he is fondly attempting to continue, and there's the legacy that is attempting to be subverted by some old foes. And then there's the legacy that he has no idea about, which, of course, the Marvel universe provides."

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