5. Barry Zito
Already a three-time All-Star and the 2002 AL Cy Young winner by the time he joined the San Francisco Giants, left-hander Barry Zito cannot be forgotten.
While his best seasons came in an Oakland Athletics uniform, he was still a solid pitcher during his time with the Giants, winning 63 games with a 4.62 ERA in seven seasons.
The highlight of his Giants career came during the 2012 postseason, when he followed up a brilliant NLCS start (7.2 IP, 6 H, 0 ER) by outdueling Detroit Tigers ace Justin Verlander in Game 4 of the World Series, allowing six hits and one earned run in 5.2 innings to finish off the sweep.
Among his career highlights, Zito is one of just 18 pitchers to record a win against every MLB team. He finished his 15-year MLB career at 165-143 with a 4.04 ERA in 2,576.2 innings.