A historical figure was an individual who was celebrated for their historical (rather than current) contributions to society.
In 2368, Data became interested "romantic historical figures" such as Anne Boleyn and Henry VIII, following Jenna D'Sora's breakup with Jeff Arton. (TNG: "In Theory")
The Doctor's holoprogram EMH program 4C contained several noted historical figures, including Mahatma Gandhi, Lord Byron, Socrates, T'Pau, and Marie Curie, so as to include their character traits from what he described as "the most accomplished figures in history," specifically "scientists, poets, philosophers, and saints." (VOY: "Darkling")
In the far future, a professor educated her students about great historical figures from Starfleet history, including Brad Boimler, for his Boimler Effect, and Miles O'Brien, for being the greatest engineer in all of Starfleet. (LD: "Temporal Edict")