Luigi Risotto is the proprietor of Luigi's.
Luigi owns an Italian restaurant in Springfield, that serves average Italian food. Luigi often treats his customers rudely, insulting and belittling them; at times under his breath, at other times in a conversational tone, and sometimes shouting the slurs to the (unseen) chef Salvatore. Luigi seems to have some connections to the mafia. Local gangster Fat Tony is a frequent customer at his restaurant, despite the fact that he was one of the targets of Fat Tony's plan to get rid of all other food retailers except Marge's. He does not actually speak Italian, only "fractured English" with a strong Italian accent, as did his parents. He says the phrase, "I guarantee," a lot.
When Homer was a food critic, he gave Luigi's eatery a poor review; in retaliation, Luigi hired a friend to place a horse's head in Homer's bed (a reference to The Godfather). Homer subsequently ate the head and gave it a bad review.His one on-screen companion is Giuseppe the monkey.
He can play accordion.
In The Simpsons: Tapped Out (app for Android and iOS), Luigi has a slip of his tongue and reveals his true accent is British. He quickly realizes his mistake and returns to his Italian.
Behind the Laughter
Luigi is a parody of the "Italian pasta/pizza chef" stereotype, but seems to be aware of his status as a stock character. His surname is a reference to the Italian food risotto. He also seems to be a parody of Tony ("Lady and the Tramp") He also sounds like the Mario brothers.