卡宾（Carbene），又称碳烯、碳宾，是含二价碳的电中性化合物。卡宾是由一个碳和其他两个基团以共价键结合形成的，碳上还有两个自由电子。最简单的卡宾是亚甲基卡宾，亚甲基卡宾很不稳定，从未分离出来，是比碳正离子、自由基更不稳定的活性中间体。其他卡宾可以看作是取代亚甲基卡宾，取代基可以是烷基、芳基、酰基、卤素等。这些卡宾的稳定性顺序排列如下：

氮杂环卡宾是一类较新颖的卡宾，也译作稳定卡宾，具有特殊的稳定性，有些可以无限期的保存。典型的氮杂环卡宾中，卡宾的二价碳位于咪唑环系、1,2,4-三嗪环系或与两个取代氨基相连的碳上。

In chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is R-(C:)-R' or R=C:.

The term "carbene" may also refer to the specific compound H₂C:, also called methylene, the parent hydride from which all other carbene compounds are formally derived. Carbenes are classified as either singlets or triplets, depending upon their electronic structure. Most carbenes are very short lived, although persistent carbenes are known. One well-studied carbene is dichlorocarbene Cl₂C:, which can be generated in situ from chloroform and a strong base.