Carpentier allegedly weighed around 105 when he began his career. He did win a French Bantamweight title, and certainly won continental titles from Welterweight upwards.
Willie Pastrano started out as a featherweight. Barbados Joe Walcott fought several guys who weighed over 200 pounds. Ted (Kid) Lewis likely started out as a flyweight (he weighed 116 pounds in his 43rd fight after 1-1/2 years as a pro) and fought Georges Carpentier for the European heavyweight title).
Stanley Ketchell started his pro career as a lightweight and of course fought Jack Johnson for the heavyweight title.