Greg Maddux had 999 walks in his career. This is the fewest walks allowed by any pitcher with 3,000 or more strikeouts. Maddux was known for his control and ability to pitch to contact. He was also able to change speeds and locations well, making it difficult for batters to hit him.
The Maddux Mastery Quiz: Untangling the Legendary Pitching Prowess of Greg Maddux