梅西耶天体（英语：Messier object），又名梅西叶天体，指由18世纪法国天文学家梅西耶所编的《星云星团表》中列出的约一百个天体。梅西耶本身是个彗星搜索者，他结集这个天体目录是为了把天上形似彗星而不是彗星的天体记下，以方便他寻找真正的彗星时不会被这些天体混淆。现在知道，梅西耶天体中有星系、星云和星团。但是对于仅仅对寻找彗星有兴趣的梅西耶，统统把它们归成一类，即类似彗星的天体。

1774年发表的《星云星团表》第一版记录了45个天体，编号由M1到M45。1780年增加至M70。翌年发表的《星云星团表》最终版共收集了103个天体至M103。现时梅西耶天体有110个，M104至M110是后人把由梅西耶及他朋友皮埃尔·梅香（Pierre Méchain）所发现而未被编入《星云星团表》的天体所加入的。

The Messier objects are a set of over 100 astronomical objects first listed by French astronomer Charles Messier in 1771. Messier was a comet hunter, and was frustrated by objects which resembled but were not comets, so he compiled a list of them, in collaboration with his assistant Pierre Méchain, to avoid wasting time on them. The number of objects in the lists he published reached 103, but a few more thought to have been observed by Messier have been added by other astronomers over the years.