Gonk

A gonk was a 1960s toy, described by Susan Foreman as "stuffed Humpty Dumpty-like things, huge eggheads with exaggerated faces and tiny limbs". Upon first seeing one, the First Doctor expressed its impracticality as a species, before being informed that it was simply a toy:

"Does this represent an actual earthly lifeform?’ Arms stick out where the ears should be. Where would a digestive system be located in this giant skull, do you think? The legs wouldn't support the weight of the head. No, it’s most impractical. It’d never survive."

- First Doctor

Six-year-old Malcolm's favourite toy was his gonk, who he named Cowboy Gonk. The gonk had "a black moustache, a tiny Stetson and holsters around its jowls". To him, his most precious object, he offered it to the Doctor on 2 April 1963 in hope that he'd save humanity for them from the Cold. Pleased, the old man called it "a feat of imagination", and decided that humanity was worth saving, at the very least for its originality. (PROSE: Time and Relative)