Fire & Blood (mentioned)|
The Rogue Prince (mentioned)
Mellos was a Grand Maester during the reign of Viserys I Targaryen. He replaced Grand Maester Runciter in 112 AC. He encouraged the match between Laenor Velaryon and Princess Rhaenyra Targaryen, despite the fact that Laenor was known not to be interested in women. He also counselled forgiveness for the king's brother, Prince Daemon Targaryen. When King Viserys I Targaryen fell and sliced his hand open on the Iron Throne, Mellos was unsuccessful in treating the laceration. Princess Rhaenyra flew her own maester, Gerardys, from Dragonstone to treat her father. Gerardys swiftly amputated two of the King's fingers, saving his life. 
After Mellos passed away, Rhaenyra recommended that Gerardys take his place as Grand Maester. Queen Alicent, on the other hand, wanted Maester Alfador, who served House Hightower, named to the office. Beset from both sides, Viserys chose neither, reminding both his wife and daughter that the Citadel would decide who filled the office. Archmaester Orwyle, in the end, was selected by the conclave as the new Grand Maester.
Mellos's written accounts were used frequently by Archmaester Gyldayn in his own writings. Gyldan considered Mellos's frequent leechings to be less effective than Maester Gerardys's potions and tinctures.
What of it? I am not fond of fish, but when fish is served, I eat it.—Mellos on the match between Laenor and Rhaenyra