Dungeons & Dragons (1983)

S1E2 The Eye of the Beholder

The kids encounter a knight called Sir John, who comes to their rescue when a massive scorpion is hunting them down. Later, when Dungeon Master tasks them with confronting a beholder in a remote valley, they believe Sir John would be the ideal companion for the mission. However, there's a catch: Sir John is actually quite cowardly at heart.