I have spent the last few days skimming Bertolt Brecht's FBI file. Some parts have been redacted, but there is still plenty to read. It's about 300 pages long, and covers 1941 to 1947. The FBI was quite exhaustive in their surveillance, both visually and electronically.
The link to part one is here: http://vault.fbi.gov/Bertolt%20Brecht%20/Bertolt%20Brecht%20Part%201%20of%204/view
There are plenty of people that you've heard of mentioned in the file: Brecht; his wife; his mistress; his musical collaborator Hans Eisler; his children, Barbara and Stefan; Peter Lorre; Heinrich Mann; Charles Laughton; Elsa Lancaster; Elisabeth Bergner; etc. I think the only one of them still alive is Eric Bentley.
I'm not sure why the FBI chose Brecht's file to highlight. Most of the informants' names are blacked out- the only one that I recognized was Mrs. Robert Siodmak (we'd watched "The Killers" a few nights before).