Michael Cera was 9 in What Katy Did when he played the character 'Dorry Carr'.
That was over 25 years ago in 1999.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
Today he is 35, and has starred in 61 movies in total, 57 of those since What Katy Did was released.
In What Katy Did, I think Michael Cera looks: