A painting of Leif Ericson.
Leif Ericson was an 11th century Viking explorer on Earth, credited as being the first European to discover North America.
Marla McGivers adored men like Ericson and kept a painting of him in her quarters aboard the USS Enterprise.
When Khan visited her quarters in 2267, he recognized Ericson among her art collection, which he descibed as being of "bold men from the past." (TOS: "Space Seed")