蝎虎座BL型天体，（英文简称BL Lac object或BL Lac），是一类位于活动星系核心部位的天体，其名字来自其原型蝎虎座的天体BL。特征如下：

目前已知的蝎虎座BL型天体约有100个。

A BL Lacertae object or BL Lac object is a type of active galaxy with an active galactic nucleus (AGN) and is named after its prototype, BL Lacertae. In contrast to other types of active galactic nuclei, BL Lacs are characterized by rapid and large-amplitude flux variability and significant optical polarization. Because of these properties, the prototype of the class (BL Lac) was originally thought to be a variable star. When compared to the more luminous active nuclei (quasars) with strong emission lines, BL Lac objects have spectra dominated by a featureless non-thermal continuum.