Robert Downey Jr. Introduces Baby Boy Exton Elias

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Robert Downey Jr. & Susan Downey's and son Exton Elias -- NBC

Meet Robert Downey Jr.'s new bundle of joy!

"The Avengers" star showed off pictures of his 8-week-old son, Exton Elias, on Thursday's "The Tonight Show with Jay Leno."

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"I have to exercise just a little restraint," the 47-year-old joked when Leno asked him to show photos of his son with wife Susan. "I mean, if you want me to, I will."

"He's so darn cute, isn't he?" he said of his son.

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The actor has an 18-year-old son, Indio, from his previous marriage to ex-wife Deborah Falconer.

When Robert and Susan announced their pregnancy back in August, the actor joked that a girl might be the best fit for their family.

"I think we should probably try to have a girl because I don't want another male entity to have to compete," he said at the time. "I don't want Indio to feel there's another boy in my life. But I don't know what we'd have to do [to have a girl]. Do we have to put it in a spoon and hang it upside-down?"

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Robert and Susan wed in August 2005.

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