Antonio Alfonseca (; Spanish pronunciation: [an'tonjo alfon'seka]; born April 16, 1972) is a Dominican former relief pitcher.
He last pitched in Major League Baseball for the Philadelphia Phillies in 2007.
Alfonseca also played for the Florida Marlins (1997–2001, 2005), the Chicago Cubs (2002–2003), the Atlanta Braves (2004), and the Texas Rangers (2006).
He is known for having an extra digit on each hand and foot.