The Hope Eater, for dnd5e and Tales of the Valiant (free, open content)

The hope-eater is a horrific fiend from the Dimension of Dreams, beyond the Ethereal. It ventures out into the material world to feed on the hope of mortals, sowing doubt wherever it goes. While it plays on one's doubts, self-doubt is a more subtle thing than fear, and sneaks past the defenses of great warriors of the light to sabotage their sense of self worth. The fiend resembles a tall, gaunt owlbear, and often fights like one, while its aura of doubt goes to work on its victim's minds.

Sheet here: https://www.patreon.com/posts/106510139