Here are a few of the commonly used printers that work with Square Terminal:-
Star Micronics TSP143IIIU
Star Micronics mC-Print3 / mC-P31
Star Micronics mC-Print3 / mC-P30
Star Micronics mPOP
Epson TM-m10 (USB Interface models)
Epson TM-m20III