In a show full of hundreds of hilarious characters, it's understandable that some go without names. In Family Guy, the nameless characters normally appear in cutaway gags or in random episodes. Their purpose is simply to push a specific part of a plot arc forward and provide much-needed interaction with the main characters.
Dozens of unnamed characters have appeared over the years; Quagmire's kids have been the ultimate juvenile delinquents, while Mrs. Coyote has kept reminding her husband about the importance of hurrying up. While these characters have been memorable, others have been so hilarious that audiences wished they were main characters.
Compliment Guy
Multiverse's are often explored in superhero media, but Family Guy decides to go that route in season eight, as well. The evil genius Stewie gets his hand on a remote control device that allows people to travel between alternate universes.
Stewie and Brian then explore unique universes, including one where people are subservient to dogs, and another in which everyone is incredibly attractive. The most interesting universe they find themselves in is one inhabited by only one guy. The man does nothing but yell compliments all day from a distance. Stewie and Brian soon depart, leaving Compliment Guy with no one to praise.
Peter's Hairless Twin
Peter's Hairless Twin makes an attempt to impersonate Peter, but that doesn't work because his lack of hair ruins any chances of resemblance. He shows up when conservative billionaire Carter Pewterschmidt names Chris as the sole heir of all his fortune. This happens after Chris takes good care of him when he breaks his leg in a mall.
The incident angers Peter, who tries to do everything possible to please Chris so that he can get some of the money too. There's an unexpected twist when Peter's long-lost sibling shows up. When Peter goes outside to confront him with a shotgun, the twin shoots him, instead. He thus introduces himself as the new family head, ready to enjoy the fortune with Chris.
Stewie's Funny Brother
Stewie often does the weirdest things, and his never-seen-before brother proves to be quite similar in that regard during a cutaway gag. While everyone is grieving at Thelma's funeral, Stewie's twin brother decides to be the ultimate comedian, making statements that mourners find amusing.
The rest of the Griffins suggest that Stewie's brother is a lot more fun than him. While Stewie is always sulking, his brother is quite the opposite. This is proven once again when Stewie starts worrying about his own death at the funeral while his brother is all about having fun after the ceremony.
Joe's Mom
Joe Swanson is known for anger issues that often result in outbursts at random times. Interestingly, his mother happens to be an enabler. She is first introduced when Joe interrupts a news coverage of a price war between airlines. Seeing her son on TV, Joe's mom goes on to cheer him despite the fact that the reporter is uncomfortable.
Joe's mom also prefers to watch TV all day, something she argues is appropriate for someone of her age. In season sixteen, it's revealed that Joe's mom has died, but the cause of death is never disclosed.
The Other Brother
Chris isn't one to keep quiet about something he doesn't like. When Peter and Lois suggest hanging out at the Quahog Playhouse, Chris refuses. He explains that he hates the venue because the seats are too tiny.
A flashback scene in a cutaway gag then shows Chris stuck in one of the seats at the Quahog Playhouse. A concerned Lois brings him food and beddings before leaving. A boy sitting near Chris informs him that Lois won't be coming back. When Chris asks how he knows that, the boy says that Lois is his mother, too.
Other Meg
Peter's absurd actions eventually managed to gain him some notoriety, and he goes even further and capitalizes on the bad publicity by starting a reality show named The Real Live Griffins. A parody of The Real World, the show is meant to highlight all the quirks and oddities of the disfunctional family.
Meg isn't too happy about what's going on, so she refuses to participate in the show. Since the Griffins already have a contract, they are forced to bring in a replacement who looks like Meg. Thanks to her good looks and over-the-top antics, "Other Meg" steals the spotlight from the real Griffins, and, as a result, they quit.
Death's Mother
Among the animated sitcom's many weird characters is Death. When Peter gets struck by lightning, he almost dies, and he thus bonds with Death and organizes a date for him with Amy.
Death's mother is also introduced, appearing to show motherly concern for her son. She warns him about disrespecting her and suggests that he has no skin because he never eats his beans. She appears to have forgotten that she has no skin, too. Thanks to her excessive parenting, Death tries to avoid her.
The Jousting Drill Instructor
Peter is never quite the lucky character. This is proven once again when Mr. Weed promises to promote him to Head of Toy Development. Unfortunately, Mr. Weed dies, and everyone loses their job because his will states that the Happy-Go-Lucky Toy Factory is to be converted to the Happy-Go-Lucky Terminal Disease Institute upon his death.
Unable to find a new job, Louis reminds Peter about his dream of becoming a Renaissance Fair jouster. His attempt to get into the profession fails because the training is too intense, all thanks to the tough jousting drill instructor who keeps reminding him that he is nowhere near tough.
Greased-up Guy
Some characters in Family Guy simply exist to pump up the humor, and that's what Greased-up Guy is all about. Since his body is covered with grease, he enjoys causing havoc before running away, knowing he is too slippery to be caught.
He first appears at the Happy-Go-Lucky Toy Factory company picnic, where one of the challenges involves catching him. Most employees fail to complete the challenge, and he would make subsequent appearances in plenty of other episodes and seasons.
The Effeminate Cow
There are a couple of intriguing animal characters in the show, and the effeminate cow is one of them. The cow is often seen in diners, struggling to make up its mind on what to order.
The effeminate cow also enjoys taking ice cream, which is a dairy product. While everyone seems to enjoy the cow's company, Peter can't stand the odd character.