First of all, which season you are looking at. Season 5, 6, 7 or 8.

Anyway

Season 5: Sean Yazbeck was named the winner and hired by Donald Trump as the new Apprentice during the season finale. Lee Bienstock, the runner-up to Yazbeck, proved to be very competitive and was hired outside of television a few months later.

Season 6
Hired: Stefani Schaeffer. While she never stepped up as project manager, Stefani won the respect of many people. She was well-liked because she doesn't take credit for things and she never made any significant mistakes throughout the interview process.

Season 7
Winner/Hired: Piers Morgan

Season 8
Winner/Hired: Clint Black

Regards!!!

PS:for additional Info please refer to the following link

http://en.wikipedia.org/wiki/The_Apprentice_(U.S._TV_series)