Dick was a male Human name. It was frequently used as a nickname for men named "Richard".
The phrase "Tom, Dick, and Harry" was a term describing any ordinary guy. This phrase was mentioned in the 20th century song "Here's to the Losers". (DS9: "Tears of the Prophets")
In 2372, The Doctor explained that he couldn't use an autonomic response analysis on Teirna, who was a member of a species from the Delta Quadrant, as they had no baseline for his responses, unlike if he had been any Tom, Dick, or Harry from the Alpha Quadrant. (VOY: "Basics, Part I")