Semiarid-adapted species often harbor endophytic populations that help mitigate host plant stress. Thus, we evaluated the diversity and plant growth-promoting potential of endophytic bacteria from highly drought-resistant (HDR) (Opuntia undulata, O. stricta, and O. ficus-indica) and less-drought-resistant (LDR) (all O. cochenillifera) forage cactus cultivars. Purified isolates were characterized using BOX-PCR and grouped into 186 strains. We investigated the presence of acdS and nifH, indole-3-acetic acid (IAA), siderophore production, calcium phosphate solubilization, and osmotic stress adaptation in vitro, and these characteristics led to 25 groups at 100 % similarity. Representatives from each group were sent for 16S sequencing. Of the 186 strains, 24 were positive for acdS, 41 for nifH, 30 produced IAA, 75 produced siderophores, 15 solubilized phosphorus, and 66 supported at least one level of osmotic stress. Twelve genera were identified with 95-100 % identicality to the NCBI gene bank, including Acinetobacter, Bacillus, Burkholderia, Citrobacter, Desertihabitans, Enterobacter, Leclercia, Priestia, Pseudomonas, Ralstonia, Staphylococcus, and Stenotrophomonas. The HDR group had a higher proportion of acdS-and nifH-positive strains and more in vitro growth-promoting mechanisms. Although these results indicate a higher occurrence of bacteria with potential stress-reduction effects in the more resistant genotypes, this must be confirmed in plants under stressful environments.