Sylvester J. Sharky appears to be an anthropomorphic rat, with a huge droop-snoot nose upon which a pair of pince-nez spectacles are perched.
In The Golden Helmet (1952), the first story in which he appears, he provides legal advice to Azure Blue, who claims to be owner of North America, because he is a descendant of Olaf the Blue, a Viking explorer who discovered America in 901 AD. Whenever Sharky was asked to prove his client (Blue or whoever he was working for) to descend from Olaf, he replies asking the questioner to prove he isn't.
Sharky often speaks in fake legal Latin, like "Hocus, locus, jocus", which means "To the landlord belong the doorknobs".
Lawyer Sharky seldom has a large role, but he is often seen in cameo appearances.
In The Lost Charts of Columbus, believing a Phoenician prince named Hanno to have made a claim to North America before anybody else, he helped Azure Blue, now Azure "Hanno" Blue, to "prove" his kinship to Hanno.
In The Poorest Duck in Duckburg he helps Scrooge McDuck cancel Halloween by spending his money on all the Halloween stuff in Duckburg but that only makes things worse for Scrooge, but Scrooge gets his money back eventually.