XS

XS may refer to:

*"Extra Small", a size of clothing. European clothing-size standard EN 13402 defines the size code XS to refer to chest girths 78–86 cm for men's clothes and bust girths 74–82 cm for women's clothes. Manufacturers also use their own non-standard defining body measurements for this size code.
*XS (comics), a DC Comics superheroine
*XS Energy Drink, a brand name
* Xavier School, secondary school in San Juan, Metro Manila, Philippines
* ExcessComputer terms including
*XS (Perl), an interface through which computer programs written in Perl can call C language subroutines
*XS (LISP dialect), A Scheme-like dialect of LISP, for programming LEGO Mindstorms systems
*XS (Game), a 1997 FPS game made by GT interactive.
*A synthesiser in the Yamaha Motif series.

or as a Backronym for:
*Cross section
*Xiaolin Showdown