The COO (Chief Operating Officer) is the senior executive responsible for running operational execution across the company's functions. The specific scope varies significantly by company depending on what the CEO chooses to delegate and what the company structurally needs. The COO often serves as the CEO's right-hand operator and integrator across departments (sales, marketing, customer success, finance, HR, sometimes engineering) rather than running any single function. The role is highly contextual rather than universally present at venture-backed startups; many successful companies operate without a COO at all. It is the most variable and contested of the C-suite roles, with no consensus definition and significant variability in actu...