Joseph Francis Giannini (September 8, 1888 – September 26, 1942) was a shortstop in Major League Baseball who played briefly for the Boston Red Sox during the 1911 season. Listed at 5 ft 8 in (1.73 m), 155 lb., Giannini batted left-handed and threw right-handed. A native of Drytown, California, he was signed by Boston out of the University of San Francisco.

Giannini was a major leaguer whose career, statistically speaking, was only slightly different from that of Eddie Gaedel or Moonlight Graham. He appeared in one game and hit a double in two at-bats for a .500 average, without runs or RBI. As a fielder, he collected two assists and committed two errors for a .909 fielding percentage.

Giannini died in San Francisco, California, at age 54.

• Baseball Reference