writing under restrictive political regimes

do you mean books that conformed to the censorship, or ones that were blocked from publication because of the censorship?

both really

Zamyatin's "We" should fit the bill; a Russian dystopian novel that discusses issues like the individual getting crushed under social order.
Not sure how you define "successful" in the case of being subversive or satirical here, since this was banned and only released in England at first, so it probably had little to no influence on the Russian people, and I believe Zamyatin ended up asking Stalin for permission to leave the country, as he was no longer allowed to publish his texts.

I suppose Bulgakov's Master & Margarita should be mentioned too - getting the author exiled and all, but again it was not released in its native country for many years, and it took even more years before it was released in uncensored form.

So! That's probably the most obvious ones out of the way.

Undoubtedly a ton of political, social, biological etc texts have been cut down by governments, even ones that aren't necessarily considered to be "restrictive political regimes". I can't think of any off-hand though, since I'm mainly a fiction-geek.

For brief and stimulating reflections on this see James Wood's essay on George Steiner in The Broken Estate (1999).

In my opinion, all of Vaclav Havel's plays before 1990 apply. His plays were produced the world around, to great success, but could not be performed in his own country.

I'm thinking that it would be more interesting to discuss great writing that was produced in a regime of high censorship but which did not fall foul of it. Examples?