Undead Viking

It uses the same walk and swing pattern as a Skeleton, so it reads as familiar right up to the point it leaves the ground. It jumps considerably higher, and the ice caverns push them out more often than ordinary stone produces skeletons, so a depth that felt quiet elsewhere gets busy under the snow.

The usual trench trick fails here. Drop into a shallow hole to swing upward at a skeleton and the viking clears the lip and lands on your head instead. Use height rather than depth: a platform placed above its jump arc gives you the same safety, and the ice biome normally has the vertical room for it. They also carry a Compass, which is a small reason to keep killing them if you have not turned one up yet.