An overview of the known methods introducing selenium under action elemental into structures various saturated, unsaturated, and heteroaromatic selenacycles containing C–Se, N–Se, B–Se, Ge–Se P–Se bonds is presented. These include metal, iodine, bromine or chlorine exchange for direct cyclization 1-(2-bromoaryl)benzimidazoles, polyunsaturated hydrocarbons, acetylenes, propargylic amines, 3-halo...