Billy Leo Williams (born June 15, 1938) is an American former left fielder and coach in Major League Baseball (MLB) who played from 1959 to 1976, almost entirely for the Chicago Cubs.

Along with Ernie Banks and Ron Santo, Williams was one of the central figures in improving the Cubs' fortunes in the late 1960s after the club had spent 20 years in the bottom half of the league standings.

In 1972, he was again the runner-up in MVP voting after winning the NL batting title with a .333 average, adding 37 home runs and 122 RBI while leading the major leagues in total bases and slugging percentage; in both years, he lost the award to Johnny Bench of the Cincinnati Reds.

He was traded to the Oakland Athletics after the 1974 season, becoming a designated hitter in the American League (AL), and contributed 23 home runs and 81 RBI to finally reach the postseason as the team won their fifth consecutive division title.

His 392 home runs, 2,510 hits, 1,353 RBI and 4,262 total bases with the Cubs are all team records for left-handed hitters, as were his 402 doubles until Mark Grace passed him in 1999.

Williams was inducted into the National Baseball Hall of Fame in 1987,[1] and was selected as a member of the Cubs All-Century Team in 1999.

After returning to Ponca City in 1957 and hitting 17 home runs, Williams split 1958 between the Burlington Bees and Pueblo Bruins.

[6] During the 1959 season, he advanced to the Class AAA Fort Worth Cats and played 18 games for the Cubs after being called up in August.

[4][5] In 1960, he hit 26 home runs for the Class AAA Houston Buffs and played in 12 major league games after joining the Cubs in September.

[4][5] Williams joined a Chicago Cubs team that by the early 1960s featured stars such as Ernie Banks, Ferguson Jenkins, and Ron Santo.

Williams debuted with the Cubs on August 6, 1959 in a 4-2 win over the Philadelphia Phillies; as an indication of the expectations placed on him, he batted third, ahead of Banks.

His batting swing was smooth and efficient, with quick wrist action that allowed him to hit for both average and power despite his slender frame.

On July 4, in a 7-4 loss to the Phillies, he broke Bill Nicholson's team record of 205 home runs by a left-handed hitter.

[10] He paced the major leagues in batting average with a .333 mark, and posted a .606 slugging percentage with 37 home runs and 122 RBI.

[11] In August, he won his second and final NL Player of the Month Award (.438 average, 9 home runs, 29 RBI); on August 26, he broke Stan Hack's team record of 2,193 hits by a left-handed hitter, tying his career high with five hits including a pair of home runs in a 10-inning, 10-9 win over the San Francisco Giants.

In 1974 the Cubs finished in last place, with their worst record since 1966; after two years of declining production, with the lowest home run and RBI totals of his career, Williams was traded in October to the American League's Oakland Athletics for second baseman Manny Trillo and two pitchers.

[4] He retired after playing his last major league game on October 2, picking up a single in his final plate appearance in a 14-inning, 9-8 win over the California Angels.