Pizarians are an alien species of sentient pizza-slices. They all have two eyes, two arms and legs, a mouth, and does not seem to wear any clothing. They appear to be roughly the same height as short humans.
Pizarians have fought well and hard for their safety; creating the Galactic Association for the Advancement of Pizza People, spearheaded by Director Peppo Blimblom. He visited Earth shortly after it joined the Galactic Federation and witnessed, to his horror, humans eating pizza slices resembling young Pizarians. He quickly returned home and wrote a blogpost about it; "Dear Humans, Your “Pizza” is Appropriating our Culture". 
The Marinara Wars
The Marinara Wars were a collection of wars fought between Pizarians and Traflorkians. The wars took place two Pizarian generations ago. It's said that during the wars "millions of Pizarians were folded and consumed" by the Traflorkian God Emperor Pahpahj’han. Whole villages were wiped out in less than a half hour. 
The Pizarians had at one point an obesity epidemic. This was caused by, or resulted in, a large part of the Pizarian population having stuffed crust.