The Ellis Group is a stratigraphical unit of Bajocian-Oxfordian age in Alberta, Saskatchewan, Montana and Wyoming in the Western Canadian Sedimentary Basin.

It takes the name from Fort Ellis, Montana, and was first described in outcrop in the Rocky Creek Canyon by A.C. Peale in 1893.

[2] The Ellis Group is composed of shale and sandstones deposited in a marine and transitional environment.

[1] Oil is produced from the Sawtooth Formation in southeastern Alberta.

The Ellis Group laterally occurs in the subsurface in southern Alberta and northern and central Montana.