In genome-wide association study (GWAS) meta-analyses of the tail end of the BMI distribution (≥95th percentile BMI) and two SevO phenotypes [Obesity Class III BMI ≥ 40 kg/m2 and Obesity Class IV BMI ≥ 50 kg/m2] in 159,359 individuals across eleven ancestrally diverse population-based studies followed by replication in 480,897 individuals across six ancestrally diverse studies, we identified and replicated three novel signals in known loci of BMI [TENM2, PLCL2, ZNF184], associated with SevO traits. This evidence concerns the gene PLCL2 and obesity due to melanocortin 4 receptor deficiency.