Fatty
From Tardis Wiki, the free Doctor Who reference
Fatty was created by Annette Billingsley as a character in her thirty-two book series of Troubleseekers children's novels. He was an overweight child who desperately wanted to be part of the Troubleseekers group, but the the children found him annoying, so instead he followed them and tattled on them.
In a world created by fictional books Martha Jones had read, Fatty was temporarily brought to life by a Ch'otterai. (PROSE: The Mystery of the Haunted Cottage)