Nigel and Sebastian are the carnival freak boss of the "Carny" level of The House of the Dead: Overkill. Nigel is a dim-witted giant roughly three times the size of the average human whilest Sebastian is a well-versed, tumor-like growth protruding from Nigel's stomach. Nigel is apparently dependant on Sebastian for survival, and will protect his conjoined twin above all else. However Sebastian, despite being a parasitic twin, is fully capable (if crippled and unable to move himself) of surviving without Nigel.
They are initially seen gnawing on the head of a struggling mutant. Upon spotting the players, Sebastian commands Nigel to attack, excited by the prospect of "good eats".
After the battle, Nigel dies, but Sebastian still moved, only to be quickly killed as well by Issac Washington.