Idiot

Idiot was a insult used typically to suggest stupidity.

The Ninth Doctor recurringly refered to Mickey Smith as "Mickey the idiot." (TV: World War Three, Boom Town)

The Twelfth Doctor named himself "Doctor Idiot", having failed to realise that a forest had spontaneously grown across the Earth to protect the planet from a solar flare. (TV: In the Forest of the Night)