Geodorcus montivagus is a large flightless species of stag beetle endemic to New Zealand.

[1] The specimen found has a body length, including its mandibles of 21.1mm.

[1] This species is known from only one female specimen found on the Victoria Range in New Zealand.

It was found in tussock at 1,220 metres (4,000 ft) above sea level.

[1] This species has been classified as "Data Deficient" with the qualifier of "One Location" under the New Zealand Threat Classification System .