Methods for the synthesis of hetaryl and ferrocenyl thioketones as well as applications of this class of organic sulfur compounds in the synthesis of both sulfur-containing and sulfur-free organic products are summarized. The most important applications relate to [2+2]-, [3+2]-, and [4+2]-cycloadditions. Aromatic thioketones react with diazomethane at −70°C, and the formed 1,3,4-thiadiazolines can be used as convenient precursors of reactive thiocarbonyl S-methanides. In contrast, the hetaryl thioketones do not form this type of cycloadducts. Reactions of hetaryl thioketones with thiocarbonyl S-methanides are proposed to occur via a stepwise diradical mechanism. Aryl and hetaryl thioketones react as prone heterodienophiles with cyclic and acyclic dienes. The first asymmetric synthesis of dihydrothiopyranes from aryl and hetaryl thioketones was performed using a L-proline-derived organocatalyst. Hetaryl thiochalcones are useful heterodienes for the preparation of hetaryl-substituted dihydrothiopyrans.