His name implies that his biology and origins is shrouded in mystery, perhaps even to himself. There are no other "onion ring things" seen in canon, possibly indicating that he is the only member of his species. Despite this, he is characterized as a jokester who likes to goof around. He has a habit of repeating everything he says, though this is not entirely consistent in the comic books.
In relation to other fast food mascots, Onion Ring Thing is quite similar to the McDonald's character Grimace, in that they are both enigmatic beings who mainly serve as comic relief. However, Onion Ring Thing is clearly identified with onion rings, whereas Grimace is only vaguely associated with milkshakes. It is possible the Burger King character "The Burger Thing" (an anthropomorphic hamburger/living portrait) is a rip-off of Onion Ring Thing.