阿伏伽德罗（Amedeo Avogadro、1776年－1856年），意大利化学家，生于都灵。全名Lorenzo Romano Amedeo Carlo Avogadro di Quaregua。1811年发表了阿伏伽德罗假说，也就是今日的阿伏伽德罗定律，并提出分子概念及原子、分子区别等重要化学问题。

阿伏伽德罗出生于意大利西北部皮埃蒙特区的首府都灵，是当地的显赫家族，阿伏伽德罗的父亲菲立波，曾担任撒伏以王国的最高法院法官。父亲对他有很高的期望。阿伏伽德罗勉强的读完中学，进入都灵大学读法律系，成绩突飞猛进，1796年获博士学位。

Lorenzo Romano Amedeo Carlo Avogadro di Quaregna e di Cerreto, Count of Quaregna and Cerreto (9 August 1776, Turin, Piedmont-Sardinia – 9 July 1856), was an Italian scientist, most noted for his contribution to molecular theory now known as Avogadro's law, which states that equal volumes of gases under the same conditions of temperature and pressure will contain equal numbers of molecules. In tribute to him, the number of elementary entities (atoms, molecules, ions or other particles) in 1 mole of a substance, 7023602214179000000♠6.02214179(30)×10, is known as the Avogadro constant, one of the seven SI base units and represented by N_A.