Playing on Center Court, Venus Williams and Sharapova -- both former world No. 1s -- battled for 1 hour, 29 minutes, with an interruption during the second set due to rain. Russia's Sharapova, 20, committed six double faults and 21 unforced errors.
She went into tournament seeded second, while Williams, 27, was seeded 23rd.
Venus Williams will face fifth-seeded Russian Svetlana Kuznetsova in the quarterfinals.
Henin, the top seed in the tournament, advanced to the semifinals with Wednesday's victory over the seventh-seeded Serena Williams. Henin will face 18th-seeded Frenchwoman Marion Bartoli, who advanced to her first-ever Grand Slam semifinal match with a 3-6, 6-3, 6-2, quarterfinal win Wednesday over No. 31 Dutchwoman Michaella Krajicek.