<p>Sliver defects are a group of low-to-medium angle misoriented grains in Ni-based single crystal superalloys that have received more attention in recent years. Occurrence of these defects can negatively affect the mechanical properties of single crystal components. Therefore, studying the mechanisms of sliver formation and its effects on the final properties of alloys is of great importance. In this article, recent studies on the sliver defects were reviewed. Accordingly, the mechanisms of sliver formation as well as factors contributing to sliver initiation were studied. Additionally, effects of slivers on the mechanical properties of single crystal superalloys were discussed. Dendrite deformation as well as dendrite fracture are the main mechanisms for the sliver formation. This is a consequence of local stress concentration on dendrites during solidification. Therefore, locations such as inclusions, pores, geometrically complex areas, mould walls, freckle channels, etc. can be considered as the potential factors that promote the sliver initiation. Sliver formation significantly degrades the creep life of single-crystal superalloys. Studies have shown that when crystallographic misorientation exceeds approximately 15°, creep life can be reduced by up to 47%. Despite the absence of a standardized criterion for predicting or preventing sliver initiation and propagation, their occurrence can be minimized through optimization of solidification parameters, careful grain selection, proper casting geometry design, and rigorous control of material purity and equipment conditions.</p>