Ornament & Crime (often abbreviated o_C or O&C) is an open-source Eurorack module project developed collaboratively by Patrick Dowling (pld), Max Stadler (mxmxmx), and Tim Churches (bennelong.bicyclist). The original 14HP module was designed by mxmxmx as a quantizing digital shift register, but the firmware grew into a polymorphic CV generator that runs a selectable suite of applications on shared hardware — four 16-bit CV outputs, an OLED display, and a Teensy microcontroller paired with a DAC8565.

The firmware ships with apps including CopierMaschine (a four-stage analogue shift register emulation), Quantermain and Meta-Q (quad quantizers with over 100 scales and microtonal/non-octaval tunings such as Bohlen-Pierce and Wendy Carlos scales), Piqued (a quad envelope generator derived from Mutable Instruments' Peaks code), Sequins (a dual step sequencer), Acid Curds (a neo-Riemannian chord generator), Captain MIDI, and Viznutcracker (a bytebeat generator). Alternative community firmwares — most notably Chysn's Hemisphere Suite and its continuation Benisphere Suite — split the module into two applet halves and add dozens of additional functions.

Because the design is open hardware (CC BY-SA 4.0 since the non-commercial term was waived in 2023), the module is sold by several third parties as full builds or DIY kits, including Magpie Modular, CCTV, Big T Music, Pusherman, and Northern Light Modular, the last of which also produces a Buchla-format version. A smaller 8HP variant called uO_C (micro Ornament & Crime) is widely available from these makers.

Ornament & Crime has 2 products cataloged on Equipboard, including Modular Synthesizers. Their gear is featured by 1 artist, with the strongest followings in Electronic, Rock, and Orchestra. Notable users include Mebitek.