X-ray-emitting, close binary systems, which involve a black hole (BH), a neutron (NS) or a white dwarf (WD) accreting from the companion, are ubiquitous in dense star clusters. Their abundance (i.e., number per unit stellar mass) and spatial distribution are important probes of a variety of dynamical processes, including binary formation and disruption, stellar mergers, and mass segregation. In this talk, I will present our recent work on the stellar X-ray populations, in particular CVs (i.e. accreting WDs), in globular clusters as well as the Nuclear Star Cluster (NSC) of our Galaxy, based on Chandra observations. In Galactic globular clusters, we find that the abundance of CVs is on average lower than that in the field, which can be understood as an efficient disruption of primordial binaries due to binary-single encounters. In the NSC, however, we find no clear sign of dynamical effects on the abundance and spatial distribution of CVs, despite the high stellar density and the presence of a massive black hole. On the other hand, we are able to place a strong constraint on the number of NS- and BH-binaries in the NSC. Some other interesting implications on these close binary systems will be discussed.