Eugen Guido Lammer (1863–1945) was a mountaineer of Austrian origin.

Along with August Lorria, he was one of the pioneers of climbing routes without help provided from professional guides.

In 1887 he attempted to climb the route Penhall in Matterhorn on the Western side, but was swept away from an avalanche.

Lammer and others were opposed to the traditional way of mountaineering.

This Austrian biographical article is a stub.