Kate McKinnon was 25 in Mr. Ross when she played the character 'Debby'.
That was over 14 years ago in 2010.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 40, and has starred in 31 movies in total, 29 of those since Mr. Ross was released.
In Mr. Ross, I think Kate McKinnon looks: