An old raven, son of Carc, chief of all ravens.
In Chapter XV, "The Gathering of the Clouds," Roac tells Thorin that "It is a hundred and three and fifty years since I came out of the egg;" in other words, Roac is 153 by the time of The Hobbit.
Smaug tells Bilbo not to trust dwarves:In return for the excellent meal [of the Company's ponies] I will give you one piece of advice for your good: don't have more to do with dwarves than you can help!Smaug-The Hobbit: "Inside Information"
Elvenking reponded that the smaug would tell if they are going to steal
Because he doesn't believe that someone has defeated Smaug & that he is dead.
A hobbit barrow is referred to as a 'smail.'