My initital, perhaps rather cynical reply was to doubt that there were actually ten politicians who had been prepared to sacrifice their careers in such a way, but I am open to being proved wrong!
Politaholic, writing on Westminster Wisdom, nominated John Hume, saying:
"I can think of one act of political altruism (or at any rate putting public interest ahead of party interest): John Hume's participation in the Hume-Adams talks. Bringing Sinn Fein into the political mainstream was something from which the SDLP could only lose. I don't think this was a misjudgement: Hume knew what he was doing."
I can think of one other example - Roy Jenkins' decision to rebel against the Labour leadership in 1972 and vote with the Tories in favour of joining the EEC. Readers will have different views as to whether this course of action was good or bad for the country, but ultimately it cost him the Deputy Leadership and the inside track in the race to succeed Wilson.
Are there more examples? If readers can find at least ten, I will duly compile the list based on your nominations.