Goblin-imps

Just a few hours before his fateful encounter with Bilbo Baggins, the creature known as Gollum had donned his magical Ring and wandered into the tunnels of Goblin-town. There Gollum had captured a Goblin-imp - a Goblin small enough for him to successfully subdue - and carried it back to his secret island.

The use of the word 'imp' here is slightly ambiguous, with two possible interpretations. In some uses, it simply describes a short or slight creature (and on that basis, Gollum merely captured a particularly small Goblin). Originally, though, the meaning was more specific, referring to a young person or child. This indeed seems to be Tolkien's intended meaning, because when Gollum later recalls the event, he thinks of the Goblin-imp as a 'nassty young squeaker'.¹ Assuming this is correct, then Gollum's unfortunate victim represents the sole record we have of a Goblin child.