The actress got her start in Hollywood playing smaller roles beginning in 2001 when she was just 23. Her first major role was in 2004's Mean Girls in which she played 17-year-old Regina (despite being 26), and shortly after that, she took on Allie Hamilton in our favorite watch-to-make-us-cry movie, The Notebook.
Since then, McAdams has stayed at the top of our favorite actresses list, taking on movies like Wedding Crashers, The Vow and Southpaw.
She even dabbled in television, playing Detective Ani Bezzerides in 2015's True Detective.
Needless to say, she's done quite a bit in her 39 years, so in honor of her birthday today, we're celebrating some of those moments...
Check out her best movie lines by launching the video above!