Natalie Portman is perhaps one of the best known Harvard graduates. The actress famously took time off from her acting career to attend college, then jokes about studying for finals in the popular Saturday Night Live sketch.

Portman recently returned to the Ivy League school for the Senior Class Day to deliver a touching and funny commencement speech. The 'Thor' actress expressed delight and gratitude over the invitation before admitting that she is still insecure about her own worthiness.

"I felt like there had some mistake, that I wasn't smart enough to be in this company," Portman said. "And that every time I opened my mouth, I would have to prove that I wasn't just a dumb actress. So I start with an apology, this won't be very funny. I'm not a comedian and I didn't get a ghostwriter. But I am here to tell you today Harvard is giving you all diplomas tomorrow. You are here for a reason."

The actress addressed the fact that her career helped get her accepted, but also made her want to be taken seriously. She fondly remembers how some classmates approached her once, claiming to be the next US President. Their confidence convinced her to do something meaningful in Harvard, but also helped her realize that she was taking herself too seriously.

"I realized that seriousness for seriousness' sake was its own kind of trophy and a dubious one," Portman said. "There was a reason I was an actor. I love what I do. And I saw from my peers and my mentors that that was not only an acceptable reason, it was the best reason.

Portman concludes that her experience in Harvard has pushed her to take artistic risks, especially with the drama 'Black Swan.' She advised the graduates to never doubt their own abilities.

The actress attended Harvard University from 1999 to 2003. She graduated with a bachelor's degree in psychology.