For Hitler, the rights to the original text of Mein Kampf (and probably many of his other writings) went to Bavaria after he died.

However various translations and abridgements were made with their own copyright.

Houghton Mifflin owns the rights to the US version of Mein Kampf, which was published in the 30s with a lot of the Hitler-iest parts removed (the rights are separate from the British version even though the text is identical). During WW2 and even up until the 1970s, the US government confiscated the royalties that were owed to Hitler.

Houghton Mifflin was eventually able to purchase the full rights. After an article in 2000 about how profitable it was, they started donating the profits to Holocaust-related charities. A few years ago they decided to go back to pocketing the money.