In this chapter, selected observational programs of merging galaxies, groups, and clusters are presented, and their reported results summarized. For each, neutral, low-, intermediate-, and high-ionization gas is examined separately. Various findings appear to indicate that comparing absorption to the “nearest galaxy,” the “most massive galaxy,” or the “central galaxy,” can strongly influence the inferred conclusions from the studies. The results that appear to agree between the various studies, show that compared to the CGM of member galaxies, the metal-line selected IGrM gas appears to be both relatively optically thin and kinematically quiescent in both its low- (MgII) and high-ionization (OVI) phases. Clusters, on the other hand, surprisingly appear to have neutral gas deep into their cores and, within the virial radius of the cluster, the sizes of the CGM of the individual member galaxies appears to be diminished compared to galaxies residing outside the virial radius. At the time of this writing, the study of the CGM in the IGrM and ICM environment is a developing area of study.