Capsule collider
A collision shape shaped like a cylinder capped by two hemispheres — the standard body proxy for characters because it slides over edges and steps without snagging.
A capsule is defined by a line segment and a radius: every point within that radius of the segment. It is the most-used collider for humanoids and creatures in game physics because its rounded ends have no sharp corners to catch on stairs, doorframes or terrain seams, and the capsule-vs-anything distance test is cheap — reduced to the distance from a line segment to the other shape.
Character controllers sweep a capsule through the world each frame (a shapecast) to resolve movement, slopes and step-up. Against a box it gives smoother wall-sliding; against a sphere it covers an upright body without wobble. Standard in Unity, Unreal, PhysX and Bullet.