Tom, Dick, and Harry used to refer to ordinary people in general.

☞ This expression is first recorded in an 18th-century song: 'Farewell, Tom, Dick, and Harry. Farewell, Moll, Nell, and Sue'. It is generally used in mildly derogatory contexts (he didn't want every Tom, Dick, and Harry knowing his business) to suggest a large number of ordinary or undistinguished people.