DRYOS (also stylized as DryOS) is a proprietary real-time operating system made by Canon and is used in their digital cameras and camcorders.

Since late 2007, DIGIC-based cameras are shipped using DRYOS. It replaces VxWorks from Wind River Systems which has been used before on DIGIC II and some DIGIC III equipped cameras. DRYOS had existed before and was in use in other Canon hardware, such as digital video cameras and high-end webcams.

DRYOS has a 16-kilobyte kernel module at its core and is currently compatible with more than 10 CPU types. It provides a simulation-based development environment for debugging. Canon also developed a USB- and middleware-compatible device driver for file systems and network devices, e.g. video server.

DRYOS aims to be compatible with μITRON 4.0 and with POSIX.