This dataset contains main and supplemental data tables for a chapter of the doctoral dissertation by Zachary S. Cooper at the University of Washington School of Oceanography. The chapter is titled "Chapter 4: Evolutionary divergence of Marinobacter strains in cryopeg brines as revealed by pangenomics". Briefly, this chapter contains pangenomic analyses of novel genomes of the bacterial genus Marinobacter that are compared with representative species of the genus to discern evolutionary history and functional capabilities of this species in the extreme cryopeg environment. The main data tables include lists of genomes used in the analyses and their characteristics as described in the dissertation chapter. The supplemental data tables include gene cluster annotations with COGs (S1), functional frequencies across the pangenome (S2), functional enrichment analysis (S3), KEGG annotations (S4), KEGG pathway completion values (S5), average nucleotide identity values (S6), alignment coverage values (S7), and horizontal gene transfer analysis summaries (S8). The tables were produced from the combination of outputs of the bioinformatic programs Anvi'o, KEGG KofamKOALA, KEGG Decoder, PyANI, and HGTector2. Details on the methods and interpretations of this data are included in the dissertation.