Aztec Code is a 2-dimensional bar code created by Andrew Longacre, Jr. and Robert Hussey in 1995, and published by AIM, Inc. in 1997. It is patented (US Patent 5,591,956) but released into the public domain and published as the ISO/IEC 24778:2008 standard (and paywalled as usual for ISO standards).
It resembles a QR code in appearance, but with a "square bullseye" in the center (which perhaps resembles how dart boards would look in the cubical Bizarro world). Data is encoded concentrically around the center. This system can encode the ISO 8859-1 8-bit character set.
This system is used in some bills and tickets, especially in Europe.