Michael Joseph "King" Kelly (1857-1894) was baseball's first superstar. Breaking in with the Cincinnati Reds in 1878, his brilliance with the bat and his utter fearlessness on the basepaths earning him the nickname "The King of Baseball," which was soon shortened to just "King."

The flamboyant Irishman won national renown by leading Cap Anson's Chicago White Stockings to five pennants in seven seasons from 1880-1886, while playing all nine positions. Always impeccably dressed in the latest fashions when he was off the field, Kelly's handsome face and brash style of play were soon featured prominently on billboards and in newspapers across the land, and are credited with drawing many new fans to the game. Kelly's 1887 trade to the Boston Braves for a mind-boggling $10,000 was by far the largest such deal in baseball's early history and led Chicago fans to organize a season long boycott (except when the Braves came to town).

In 16 seasons, Kelly played for eight championship teams, batting .300 or better in eight different seasons. He led the National League in hitting twice, in 1884 (.354) and 1886 (.388). But the most dazzling aspect of Kelly's game was his basestealing prowess, as he stole 50 or more bases in 5 consecutive years from 1886 to 1890 (including a league-high 87 in '87, his first year after the $10,000 trade), and probably stole many more bases in the years before that, as 1886 was the first year in which stolen base records were kept. Kelly was one of the first players to perfect the modern hook slide, leading his fans scream the dramatic cheer when ever he took off for second base: "Slide Kelly, SLIDE!" The cheer inspired a popular saloon song of the same name. The chorus went:

Slide, Kelly, slide!
Now stay there, hold your base!
If someone doesn’t steal ya,
And your batting doesn’t fail ya,
They’ll take you to Australia!
So slide, Kelly, slide!

Kelly was also known for his cleverness, and his willingness to bend the rules. In one game, during his tenure as player manager of the Braves, a pop foul drifted toward where he sat in the Boston dugout. Thinking quickly, he leapt off the bench, cried out "Kelly now catching for Boston," and made the catch for out number 3, inspiring a rule change regarding player substitutions. Another time, Kelly was playing right field when darkness began to fall in an extra-innings contest. With two outs in the twelfth inning, a scorching line drive was hit toward Kelly, who promptly raced back into the dusk and made what appeared to be a dazzling leaping catch for the third out, at which point the umpire called the game on account of darkness. As Kelly trotted off the field, his teammates asked him where the ball was. "How the hell would I know?" he said. "It was a mile over my head."

In an age when baseball salaries were often not enough to support a lifestyle as flamboyant as his own, Kelly supplemented his income by appearing in stage performances and vaudeville acts in the off-season, and wrote the first baseball autobiography, Play Ball: Stories of the Ball Field in 1888. When Kelly first learned of the $10,000 trade to Boston, he groused that "Horses are sold, not ballplayers." But he soon changed his tune when White Sox owner A. G. Spalding promised him that the Braves would increase his salary, responding, "If you can get me $5,000, I don't care a damn if you sell me for a hundred thousand." The Braves ultimately refused to pay any more than $2,000, but Kelly got his $5,000 when the Braves' owners agreed to pay him a $3,000 bonus for the right to use his photograph and likeness in advertising.

By the 1890s, Kelly's hard partying lifestyle began to catch up to him. Although he took pride in never missing a game, Kelly was known to stay out all night long, and rarely slept in his own bed, and Cap Anson was not complimenting Kelly when he griped, "There's not a man alive who can drink Mike Kelly under the table." His once powerful body began to give way, and as his speed waned, Kelly drifted out of baseball, finally retiring for good in 1893 and opening a saloon. In 1894, en route to Boston to appear in a show at the Palace Theater, he contracted pneumonia and was taken to a nearby hospital. As attendants carried him in, they dropped the stretcher and Kelly tumbled to the floor. "That's my last slide," he quipped. He died later that day, at the age of 36.

Although they had never gotten along as manager and player, Cap Anson chose Kelly as the starting catcher of the All-time greatest baseball team he was asked to name in 1918. Kelly was elected into the Hall of Fame by the Veterans Committee in 1945.