8. Rachel Menken
Showcase Episode: "Babylon"
Don's coolest girlfriend, hands down. The Jewish department-store magnate understands Don well enough to see through his let's-run-away fantasies: "What are you, 15 years old?" But she never relinquishes her hold on him, even after she becomes Mrs. Tilden Katz. (Or after Maggie Siff becomes a star on Sons of Anarchy.)