Dowager King/Queen - Neutral, will work if there's nothing better suggested
Statesman/Stateswoman - Acceptable.
The other three - slightly-opposed (seem a bit out-of-place for the role) but great brainstorming
If you don't mind, which government types would you match them to? Thus far, I'm thinking monarchy (Dowager King), theocracy (Prince), democracy (Statesman), republic (Statesman), tyranny (Royal). Anarchy can probably just be left with default Royal, since its short-lived.