Reese Witherspoon was 32 in Monsters vs Aliens when she played the character 'Susan Murphy / Ginormica (voice)'.
That was over 15 years ago in 2009.
Today she is 48, and has starred in 61 movies in total, 28 of those since Monsters vs Aliens was released.
In Monsters vs Aliens, I think Reese Witherspoon looks: