单型（英语：Monotypic）在生物分类学上，是指一个分类群中只含有唯一的一个类型。而植物分类学及动物分类学之间，对「单型」的用法又不甚相同：

In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. Although the phrase appears to indicate that a taxon has a single type specimen (with no syntypes, lectotypes, or other types) and no heterotypic/junior synonyms, that is not the usage.