This review discusses the Inhibitor of Apoptosis (IAP) family of proteins, which were first discovered in baculoviruses and have since been found to play a crucial role in suppressing apoptosis in mammalian cells. IAPs are characterized by the presence of a baculoviral IAP repeat (BIR) domain, which is essential for their anti-apoptotic function. The structure and function of IAPs have been extensively studied, revealing that they can inhibit caspases directly, thereby blocking the execution of apoptosis. The IAP family includes several human proteins such as XIAP, c-IAP1, c-IAP2, NAIP, Survivin, and BRUCE, each of which has distinct expression patterns and functions in various tissues and developmental stages. Overexpression of these proteins has been linked to cancer, and their role in neuronal cell death and ischemic injury is also discussed. The review highlights the evolutionary conservation of IAPs across different species, including insects, and their involvement in signal transduction pathways, particularly those activated by the TNF receptor family. Insights from studies in insects, such as *Drosophila*, have provided valuable information about the mechanisms by which IAPs suppress apoptosis, including their interactions with cell death proteins like reaper, HID, and GRIM. Overall, the IAP family represents a critical group of proteins that regulate apoptosis and may serve as therapeutic targets for various diseases.This review discusses the Inhibitor of Apoptosis (IAP) family of proteins, which were first discovered in baculoviruses and have since been found to play a crucial role in suppressing apoptosis in mammalian cells. IAPs are characterized by the presence of a baculoviral IAP repeat (BIR) domain, which is essential for their anti-apoptotic function. The structure and function of IAPs have been extensively studied, revealing that they can inhibit caspases directly, thereby blocking the execution of apoptosis. The IAP family includes several human proteins such as XIAP, c-IAP1, c-IAP2, NAIP, Survivin, and BRUCE, each of which has distinct expression patterns and functions in various tissues and developmental stages. Overexpression of these proteins has been linked to cancer, and their role in neuronal cell death and ischemic injury is also discussed. The review highlights the evolutionary conservation of IAPs across different species, including insects, and their involvement in signal transduction pathways, particularly those activated by the TNF receptor family. Insights from studies in insects, such as *Drosophila*, have provided valuable information about the mechanisms by which IAPs suppress apoptosis, including their interactions with cell death proteins like reaper, HID, and GRIM. Overall, the IAP family represents a critical group of proteins that regulate apoptosis and may serve as therapeutic targets for various diseases.