figurehead (n.)

also figure-head, 1765, from figure (n.) + head (n.). The ornament on the projecting part of the head of a ship, immediately under the bowsprit; sense of "leader without real authority" is first attested 1868.

You may say that the king is still head of the State, and that this is a sufficient basis for loyal feeling; certainly, if he were really so, and not a mere ornamented figure-head on the ship of state. [James Hadley, "Essays Philological and Critical," London, 1873]