Apoptotic adaptor molecule that recruits caspase-8 or caspase-10 to the activated Fas (CD95) or TNFR-1 receptors (PubMed:7538907, PubMed:23955153, PubMed:19118384, PubMed:20935634, PubMed:16762833, PubMed:24025841). The resulting aggregate called the death-inducing signaling complex (DISC) performs caspase-8 proteolytic activation (PubMed:7538907, PubMed:19118384, PubMed:20935634, PubMed:16762833). Active caspase-8 initiates the subsequent cascade of caspases mediating apoptosis (PubMed:16762833). Involved in interferon-mediated antiviral immune response, playing a role in the positive regulation of interferon signaling (PubMed:21109225). Can self-associate (PubMed:19118384, PubMed:20935634). Interacts with CFLAR, PEA15 and MBD4 (PubMed:10442631, PubMed:12702765). When phosphorylated, part of a complex containing HIPK3 and FAS (PubMed:11034606). May interact with MAVS/IPS1 (PubMed:16127453). Interacts with MOCV v-CFLAR protein and PIDD1 (PubMed:10825539). Interacts (via death domain) with FAS (via death domain) (PubMed:21109225, PubMed:16762833, PubMed:20935634). Interacts with CASP8 (PubMed:16762833). Interacts directly (via DED domain) with NOL3 (via CARD domain); inhibits death-inducing signaling complex (DISC) assembly by inhibiting the increase in FAS-FADD binding induced by FAS activation (By similarity). Interacts with RIPK1, TRADD and CASP8 (By similarity). Component of the AIM2 PANoptosome complex, a multiprotein complex that drives inflammatory cell death (PANoptosis) (By similarity). Interacts with stimulated TNFRSF10B (PubMed:18846110). Interacts with stimulated TNFRSF10B (By similarity). (Microbial infection) Interacts with human papillomavirus 16/HPV16 protein E6. (Microbial infection) Interacts with molluscum contagiosum virus proteins MC159L/v-CFLAR and MC160L. Expressed in a wide variety of tissues, except for peripheral blood mononuclear leukocytes. Contains a death domain involved in the binding of the corresponding domain within Fas receptor. The interaction between the FAS and FADD death domains is crucial for the formation of the death-inducing signaling complex (DISC). (Microbial infection) Glycosylated at Arg-117 by enteropathogenic E.coli protein NleB1, C.rodentium protein NleB and S.typhimurium protein Ssek1: arginine GlcNAcylation prevents recruitment of caspase-8 or caspase-10 to the activated Fas (CD95) or TNFR-1 receptors. The disease is caused by variants affecting the gene represented in this entry.