George J. Popplein (August, 1840 – March 31, 1901) was an American baseball player who appeared in one professional game for the Baltimore Marylands during the 1873 season.

According to Paul Batesel, Popplein was a member of the Pastimes beginning in 1861, made its first team in 1863, and remained with the club through 1871,[1] while Peter Morris notes that he played only sporadically after 1867.

[2] On July 11, 1873, Popplein appeared at third base and center field for the Baltimore Marylands.

[1][2] Popplein worked manufacturing fertilizer and paint both during and after his baseball career.

[3] By 1890, he owned the Popplein Silicated Phosphate Company, where he worked as a chemist.