Basil of Baker Street is the titular protagonist of The Great Mouse Detective.He is the greatest detective of the mouse world, able to crack any case. His specialty is figuring out clues by observation and deduction. Basil is also a master of disguise and has a trained hound named Toby to help him track down criminals.He plays the violin, and is an expert in chemistry and chess, besides cobbling together several remarkable contraptions. A very untidy fellow, Basil concentrates so much on the case at hand, that he treats others rather rudely at times.Basil is hired to stop his nemesis the evil Professor Ratigan from taking over the British Empire. By the film's end, Dr. Dawson has become Basil's partner in crime detection.He is the mouse version of the great detective Sherlock Holmes and resides at 221 1/2 Baker Street, London, under the floorboards of Holmes' famous address.He appears as a guest in 3 episodes of House of Mouse.