[jtzxkpvw] First against the wall when the revolution comes

Who should be assassinated / executed / otherwise incapacitated when consolidating power, to eliminate and prevent formation of opposition?

Seemingly obvious are leaders of the opposition, but after that things become less obvious:  People who could potentially become leaders of the opposition.  Any competent people who could potentially be useful to the potential opposition, not necessarily as a leader (but they could be potentially useful to your side as well).  Who else?  And how can one find these people?  Answering these questions​ requires understanding how society operates and adapts in response to changes.

Inspired by real mass political executions, e.g., Katyn, in which the Soviets executed a great many competent Polish people, seemingly with considerable success: it took many generations for effective opposition to form.

Vaguely similar is brain drain, which also weakens a region by depriving it of competent people.