Bacteria from the Turicibacter genus are prominent members of the mammalian gut microbiota and are associated with alterations in dietary fat and body weight, but the specific connections between these symbionts and host physiology are poorly understood. We genomically and phenotypically characterized a diverse set of mouse-and human-derived Turicibacter strains, and found they group into three clades that differ in their transformations of bile acids. We identified Turicibacter bile salt hydrolases that confer strain-specific differences in bile deconjugation. Colonization with individual Turicibacter strains led to changes in host bile acid profiles, generally aligning with those produced in vitro. Further, colonizing mice with another bacterium expressing bile-modifying genes from these strains decreased serum cholesterol and triglycerides, as well as adipose tissue mass. This work identifies genes that enable diverse Turicibacter strains to differentially modify host bile acids and lipid metabolism, and positions multiple Turicibacter strains as candidates for altering host fat biology.