Warning! Potential spoilers ahead.
“If you haven’t been following my investigations into the new creature, I’ll fill you in. A porg is a creature from Star Wars: The Last Jedi that inhabits Ahch-To. They’re a part of the ecosystem of the planet and are a sacred creature from the sound of things around the set last year. Luke Skywalker seems to care for the creatures and there is a connection between the creatures of the planet and the Force. There are moments where Chewbacca and Artoo-Detoo interact with them and care for them.
Some of the porgs have a small amount of additional coloring. I believe perhaps the male porgs have orange feathers on their head and the females do not. Here is a really solid look at a porg thanks to the art stylings of Lumberjack Nick as dictated by me:
The creatures are adorable. The puppets are complex and they look really cool and lifelike in the film. The eyes are solid black but somewhat reflective. Obviously, give some leeway to the style in which they are drawn here, but that is what a porg will look like.”
Read more at MakingStarWars.net.