Cosmic Toad

A Cosmic Toad, also known as a Star Toad, is a Toad from space in Super Mario Galaxy. They live in various Toad Houses in the galaxy.

The Cosmic Toads help Mario on his journey, teaching him how to use Boost Stars, his new moves, and helping him as much as possible. They are often seen with Space Rabbits. In fact, recent videos seem to show a Space Rabbit turn into a Cosmic Toad (see here). Therefore, (at least some, if not all) Space Rabbits are really Cosmic Toads.

They also generously give Mario Star Shards when they see him, though Mario has to help them with numerous things as well. The Cosmic Toads look similar to regular Toads, though they have several changes, such as their Mushroom heads have stars instead of dots on them, they wear oxygen helmets (so it seems), and their heads are somewhat thinner and taller.

The Starshade Bros. from Mario & Luigi: Superstar Saga are very likely canditates for being Cosmic Toads, as they wear helmets (as it looks), have starred mushroom caps, and are somewhat taller than the other toads in the game. Not to mention the fact that they are found in Stardust Fields.