is a powerful model to study how lipids affect spermatogenesis. Yet, the contribution of neutral lipids, a major lipid group which resides in organelles called lipid droplets (LD), to sperm development is largely unknown. Emerging evidence suggests LD are present in the testis and that loss of neutral lipid- and LD-associated genes causes subfertility; however, key regulators of testis neutral lipids and LD remain unclear. Here, we show LD are present in early-stage somatic and germline cells within the testis. We identified a role for triglyceride lipase () in regulating testis LD, and found that whole-body loss of leads to defects in sperm development. Importantly, these represent cell-autonomous roles for in regulating testis LD and spermatogenesis. Because lipidomic analysis of mutants revealed excess triglyceride accumulation, and spermatogenic defects in mutants were rescued by genetically blocking triglyceride synthesis, our data suggest that -mediated regulation of triglyceride influences sperm development. This identifies triglyceride as an important neutral lipid that contributes to sperm development, and reveals a key role for in regulating testis triglyceride levels during spermatogenesis.