Studies in recent years have uncovered a diverse set of eukaryotic receptors that recognize lipopolysaccharide (LPS), the major outer-membrane component of gram-negative bacteria. Indeed, Toll-like Receptors, G-protein coupled receptors, Integrins, Receptor-like kinases, and caspases have emerged as important LPS-interacting proteins. In this Review, the mammalian receptors that detect LPS are described. I highlight how no host protein is involved in all LPS responses, but a single lipid (phosphatidylinositol 4,5-bisphosphate) regulates many LPS responses, including endocytosis, phagocytosis, inflammation and pyroptosis. I further describe LPS response systems that operate specifically in plants, and discuss potentially new LPS response systems that await discovery. This diversity of receptors for a single microbial product underscores the importance of host-microbe interactions in multiple kingdoms of life.