Speculation that the two Oscar winners are dating heated up after the two were seen vacationing together in Hawaii, People reports.
Theron flew to Hawaii and reportedly stayed at Penn's beachfront home in Oahu. After Theron, 38, and Penn, 53, both rang in the new year on the island, they were then also spotted getting off of the same flight to Los Angeles on Wednesday. They were also both photographed leaving Theron's house, but in separate cars.
The two were first rumored to be more than friends in 2010, shortly after Theron split from her longtime boyfriend, Stuart Townsend.
Penn, whose ex-wife Wright recently got engaged to Ben Foster, can currently be seen in The Secret Life of Walter Mitty. Theron will next star in Seth MacFarlane's western, A Million Ways to Die in the West.
What do you think of the pairing?