Among the very first examples of hyper-Kahler manifolds given by Calabi in 1979, there were the cotangent bundles of complex projective spaces, T-star-CPn. Later on, many more examples of hyper-Kahler metrics on cotangent bundles of Kahler manifolds were shown to exist. Finally, Kaledin (1997) and Feix (1999) proved that a real-analytic Kahler metric on a complex manifold M can always be extended to a hyper-Kahler metric in a neighborhood of M in T-star-M. Although these mathematical proofs are rather technical and involved, there exists a streamlined physical construction which leads to the same results and is based on the concept of supersymmetry. As is well-known, four- and five-dimensional N = 2 supersymmetric nonlinear sigma-models possess the property that their target spaces are hyper-Kahler manifolds. The physical construction consists of providing a manifestly N = 2 supersymmetric nonlinear sigma-model whose target space can be shown to be (a neighborhood of the zero section in) the cotangent bundle T-star-M of a Kahler manifold M. This talk will review the salient properties of such supersymmetric nonlinear sigma-models with eight supercharges.