Investigator may refer to:

• Clinical investigator, an investigator involved in a clinical trial
• Detective, a person who investigates crimes, can be a rank and job in a police department, state or federal employee, or a civilian called a private detective
• Investigator Strait, a body of water lying between Yorke Peninsula, on the Australian mainland, and Kangaroo Island in South Australia
• New investigator, a designation for less experienced researchers
• Principal investigator, the lead scientist for a particular well-defined science project
• Private investigator, a person who does not work for the police or government, but who undertakes investigations
• UN Special Investigator, a United Nations appointee, charged with investigations or auditing in a specific matter