Leonardo DiCaprio is celebrating his 39th birthday today, and we're not quite sure how to feel about it. On the one hand, we can't believe that the little guy from Growing Pains has built such an illustrious film career, but on the other, it makes us feel pretty ancient. After all, watching Titanic on VHS and listening to the Romeo + Juliet soundtrack on repeat feels like yesterday. Despite his constant Hollywood presence and multitude of Teen Beat covers, Leo successfully escaped the child star curse. And even though that Oscar statue still eludes him, we can all agree that Leo has become one of the most talented and sought-after actors of our time. In honor of his big day, we've charted Leo's evolution from teenage dream to A-list heartthrob. See the full transformation when you keep reading.