In a group of animals (usually a litter of animals born in multiple births), a runt is a member which is smaller or weaker than the others. Due to its small size, a runt in a litter faces obvious disadvantages, including difficulties with competing with its siblings for survival and possible rejection from its mother. Also in a domestic dog litter, most puppies would have to make room for the runt to get milk from the mother. Therefore, in the wild, a runt is less likely to survive infancy.
Even among domestic animals, runts often face rejection. They may be placed under the direct care of an experienced animal breeder, although the animal's size and weakness coupled with the lack of natural parental care make this difficult. Some tamed animals are the result of reared runts.
Ruth, the hero Pernese dragonnet from Anne McCaffrey's novel the White Dragon, is a runt whose egg is smaller and has a harder shell than all others in the clutch. He would have died save for the intervention of young Jaxom. Despite Jaxom being heir to a Hold and as Lord Holder, forbidden from becoming a dragonrider, he cracks the shell and Impresses the dragonnet. Besides being a runt and the only white dragon (in fact hues from all dragon colors), Ruth is more intelligent than other dragons and can more easily master his teleporting powers. Ruth and Jaxom later become of critical importance for the future of Pern.
Babe, the eponymous piglet hero of Dick King-Smith's book (and the popular film based on the novel), is a runt. In fact, he was chosen for the competition at which Farmer Hoggett won him essentially because he was a runt - his runt status therefore saving his life and shaping his destiny.
Scourge from the Warriors book series was a runt. It is revealed the manga The Rise Of Scourge that he was a runt of his litter of three kittens, and was fittingly named Tiny. His siblings often excluded him in games and made fun of him and bullied him because he was smaller than them. Also, Tiny felt that his mother didn't like him as much as his litter mates. This mistreatment from his family, paired off with circumstances at the time, ultimately led him to become the most dangerous, evil and powerful cat in the town.
The title character from the novel Runt, as the name implies, is the smallest of his wolf litter.
Wilfred from the 2011 comedy of the same name was the runt of his litter.
The direwolf Ghost in the A Song of Ice and Fire book series was the runt of his litter of six pups, as well as an albino. However, the pups were adopted by the children of House Stark, and Ghost was reared by Jon Snow. In Game of Thrones the runt was played by a White Shepherd.
Wolverine of the X-Men (comics & films) is often addressed by his foes as runt due to his small height.
Seabiscuit, a famous race horse, was a runt who triumphed over larger horses. Seabiscuit's story is chronicled in an eponymous book, and a movie based on that book.
Darwin from G-Force was told that he was the runt of the litter.
Doggie Dogfoot from the book Pigs Might Fly is the runt of his litter. He would have been killed by the pig farmer but however he escaped death and got to live a normal life. He later learns to fly.