Willie Mays is one of baseball's all-time greats. A player who did it all (and did it with style), the "Say Hey Kid" was a fan favorite from the first time he stepped into the big leagues in 1951 until he retired in 1973.

LIFE.com recently published a series of never-before-seen photos of the 24-time All-Star and World Series champion. The images capture a side of Willie that, we imagine, many have never before been privy to.

There is a shot of him signing autographs for young fans, another of him eating a meal in Harlem with his landlady, and a terrific shot of Mays starting a pillow fight with teammate Monte Irvin. According to LIFE, Irvin, who was several years older than Mays, remarked in 1954: "I've got a couple of kids, 6 and 10, but when I take a road trip I've got another one on my hands. Willie is 23 years old and he'll drink maybe seven big sodas and a dozen Cokes in 12 hours."

And there are more. Many a great athlete can look graceful on the field of play, but only a select few can manage to look like superstars while drinking a glass of milk, shopping for shoes, or dealing with frenzied fans. Willie Howard Mays Jr. did it all.

ThePostGame brings you the most interesting sports stories on the web. Follow us on Facebook and Twitter to read them first!

LIFE.com has additional photos. Click here to see the full collection