Still damn good research.
Joining the army and the USO during WWII, would you call that serving as well? If not, then in that case Burt Lancaster is also possible until the freebie with answer 17.
The Westerns still did rule out someone important. Until the freebie with answer 17 it ruled out Humphrey Bogart (didn't serve in WWII and played in only 4 Westerns), perhaps the biggest actor ever.