在生物学中，最近共同祖先（英语：Most recent common ancestor，缩写 MRCA）表示一系列不同的物种拥有共同起源的那个最近的祖先。这一概念经常应用于人类的宗谱。

In biology, the most recent common ancestor (MRCA) of any set of organisms is the most recent individual from which all organisms in a group, for example a haplogroup, are directly descended. The term is often applied to human genealogy.

The MRCA of a set of individuals can sometimes be determined by referring to an established pedigree. However, in general, it is impossible to identify the exact MRCA of a large set of individuals, but an estimate of the time at which the MRCA lived can often be given. Such time to MRCA (TMRCA) estimates can be given based on DNA test results and established mutation rates as practiced in genetic genealogy, or by reference to a non-genetic, mathematical model or computer simulation. TMRCA is often given in years before current (ybc). A certain mutation can be assumed to have been formed at a time instant between the TMRCA of the previous branch in the phylogenetic tree, and the TMRCA of the mutation itself.