Ewan McGregor was in The Men who Stare at Goats with George Clooney;
George Clooney was in Burn after Reading with J.K. Simmons;
J.K. Simmons was in Megamind with Brad Pitt;
Brad Pitt was in Troy with Peter O’Toole;
Peter O’Toole was in Lawrence of Arabia with Sir Alec Guinness.
I lucked out being able to use J.K. Simmons to expand the George Clooney to Brad Pitt loop there when I realized I was going too fast.
Edit: Whoops, I need a new one. Alright, how about sticking with Star Wars and linking Hayden Christensen to James Earl Jones without Star Wars.