A healthcare proxy is the person named in a medical power of attorney to make medical decisions for someone else when that person can't make them independently. In some states, "healthcare proxy" also refers to the document itself rather than the individual, so it's worth checking your state's specific terminology. The role typically activates only after a doctor confirms the patient is unable to communicate or understand their treatment options. A good proxy knows your values and wishes well enough to make the call you would have made yourself, which is why this decision often goes to a spouse, adult child, or close friend rather than whoever's most available. Naming one in advance keeps that responsibility with someone you've chosen, not a court or default legal hierarchy.