XK may refer to:
xkcd, sometimes styled XKCD, is a webcomic created by US author Randall Munroe. The comic's tagline describes it as "A webcomic of romance, sarcasm, math, and language".
XKeyscore or XKEYSCORE (abbreviated as XKS) is a formerly secret computer system first used by the United States National Security Agency for searching and analyzing global Internet data, which it collects on a daily basis.
XKL, LLC, was founded in 1991 and develops optical transport technologies. Originally based in Redmond, Washington its headquarters are now located in Kirkland, Washington.
XK (also known as Kell blood group precursor) is a protein found on human red blood cells and other tissues which is responsible for the Kx antigen which helps determine a person's blood type.
xkoto, Inc. was a privately held developer of database load balancing software headquartered in Toronto, Ontario, Canada.
XML Key Management Specification (XKMS) uses the web services framework to make it easier for developers to secure inter-application communication using public key infrastructure (PKI).
XK is the fifth album released by singer-songwriter Brendan Croskerry and co-produced by Dave Newfeld (Broken Social Scene).
This is a list of digraphs used in various Latin alphabets. Capitalization involves only the first letter (ch becomes Ch) unless otherwise stated (ij becomes IJ).