A circlip (a combination of 'circle' and 'clip', and pronounced thus), or snap ring is a type of fastener consisting of a semi-flexible metal ring with open ends which can be snapped into place, into a machined groove on a dowel pin or other part to permit rotation but to prevent lateral movement. There are two basic types: internal and external, referring to whether they are fitted into a tube or over a shaft. Circlips are often used to secure pinned connections.

Circlips which are fitted may be removed with a pair of needle-nosed pliers or a special snap ring tool if the circlip is designed to include entry points for the pliers or tool. Alternatively, cautious leverage with a flat-headed screwdriver may be necessary in lieu of the correct tools or design of snap-ring.

Common examples include "E-clips" (e-ring) and the (both internal and external) snap ring or circlip. This general type of fasteners are sized to provide an interference fit onto (or into, in the case of an internal fastener) a groove or land when in use, such that they must be elastically deformed in order to install or remove them.

They are commonly referred to in some small engineering firms as dink. This is mainly because of the size of these components and originates from the slang term 'dinky'.