Chukk was a male Silurian who led a shelter of Earth Reptiles following the death of the previous Sea Devil leader, Daurrix. He was the brother of Okdel L'da.
Like Okdel, he believed that cooperation with humanity was the only means of the Silurian race to survive, when they awoke to a world dominated by them. Circa the 1970s, he showed the Third Doctor his shelter beneath the island of L'Ithe and its facsimile of the Hall of Heroes after the Doctor had been taken there. When Auggi D'jo questioned the Doctor, Chukk insisted that he was responsible for keeping the Silurian race alive. He was later shot and killed by a C19 operative posing as Jana Kristan. (PROSE: The Scales of Injustice)