As one of Google's earliest employees, Marissa Mayer had a hand in nearly all of Google's most important products. She was also one of the most visible, visionary spokespeople for the company. Here are five videos of high-profile appearances that show just how strong of a hand Mayer had in shaping Google and why Yahoo needs her.

Mayer's 2009 commencement address at the Illinois Institute of Technology:

Mayer foretelling the future of search in 2010 as Google's VP of search products and user interface:

Mayer talks location at South by Southwest 2011:

Mayer at LeWeb 2011 as VP of product management describing the Google+-driven future of the company: