Teary is a Dorrie-like creature that swims in the underwater lake at the Cave of Sadness, first appearing in MarioMario54321's Super Mario 64 movie The Cosmic Crystals. He's a dinosaur that appears to be fine with the sadness around the cave he lives in, and seems to be surprised that anyone made it to his lair. Nevertheless, in The Cosmic Crystals, he helped Mario to get to the crystal he was looking for.
In The Cosmic Crystals III: The End of the Star World, he's mentioned by Smiley, who lives in the Cave of Happiness, the altered version of the cave of sadness.