Cytotoxic lymphomas of the skin comprise a spectrum of peripheral T cell and natural killer cell lymphomas with primary or secondary skin manifestations. They comprise a broad, heterogeneous group of lymphoproliferative disorders, and are characterized by expression of cytotoxic proteins (TIA-1, granzyme A and B, and perforin). These lymphomas often show an aggressive clinical course. In this article a detailed description of clinical, histopathologic, immunohistochemical, and molecular characteristics of cutaneous cytotoxic lymphomas follows a brief introduction on cytotoxic lymphocytes.