Strup

 was a baby Sontaran who resided at Dorium Maldovar's nursery. He often got angry and even violent. (COMIC: Upset Sturp)

Behind the scenes
Sturp is one of the strong indicators of the parodic nature of Alien Babies!. His very existence is an in-joke for Doctor Who fans. Since Sontarans are a clone race, they do not go through a stage where they are babies.