Off the top of my head I would nominate two 12th-century people of very different fame. The philosopher and theologian Peter Abelard (1079-1142) was the most famous thinker of his day, extraordinarily smart and very popular with his students since he loved to mentally joust with other more fuddy-duddy professors and wipe up the lecture hall with them. He is probably popularly most famous for the outcome of his love affair with Heloise, brilliant in her own right, with whom he had a child that they named “Astrolabe.” Her uncle, enraged by their affair, had Abelard castrated after which he retired from public life. He and Heloise exchanged letters for the rest of his life. In one of them she calls attention to his other talent: he was, in a real sense, a “rock star”:

You had, besides, I admit, two special gifts whereby to win at once the heart of any woman — your gifts for composing verse and song, in which we know other philosophers have rarely been successful. This was for you no more than a diversion, a recreation from the labours of your philosophic work, but you left many love-songs and verses which won wide popularity for the charm of their words and tunes, and kept your name continually on everyone's lips. The beauty of the airs ensured that even the unlettered did not forget you; more than anything this made women sigh for love of you.

Unfortunately none of his secular love songs survive. For bio, I like Michael Clanchy’s Abelard: A Medieval Life though it’s been a while since I read it. Constant Mews wrote Abelard and Héloïse a decade ago. I haven’t read it but it got decent reviews if I recall.

The other star would be one who made war, not love: the Norman knight William Marshal (c. 1146-1219), who began life as a very low-end noble son and who barely eked out a living as a knight once he was cut loose from the mesnie of his uncle, who trained him with a coterie of other young knights. But William soon won enormous fame for his skill at tournaments. He would be the equivalent of an interntionally-known athlete today. He served five English kings (Henry II, his son the young Henry, who never reigned, Richard I , John I, and Henry III) and eventually was raised up as the Earl of Pembroke and regent of England for John’s infant son, Henry III. When he died he was widely hailed as “the flower of chivalry.” David Crouch’s William Marshal: Knighthood, War and Chivalry, 1147–1219 is standard, though it may have competition from Thomas Asbridge’s new book, The Greatest Knight: The Remarkable Life of William Marshal, Power Behind Five English Thrones, which I haven't read. George Duby’s William Marshal, the Flower of Chivalry is awfully fun to read but is prone to error.