Cynewulf

Cynewulf: we know very little about him. He wrote a number of the poems in the Exeter book, but received wisdom from the early 20th-century is that he didn't write the riddles therein

The Riddles were not written by Cynewulf: all evidenlce of the least value speaks against his claim. It seems fairly certain that they are products of the North. Their place as literary compositions (not as folk-riddles) in one collection, and their homogeneous artistry, which finds abundant vindication in a hundred common traits, argue strongly for a single author, though a small group of problems brings convincing evidence against complete unity. That their period was the beginning of the eighth century, the hey-day of Anglo-Latin riddle-poetry, is an inviting surmise unsustained by proof.' [Frederick Tupper (ed), The Riddles of the Exeter Book (Boston: Ginn and Co. 1910), lxxix]*

...(which suggests that the received view before this was rather that Cynewulf had written the riddles.)  He's famous for two lines, riddle-like though not technically a riddle, that had the most prodigious effect upon the imagination of J R R Tolkien:

Eala Earendel engla beorhtast
Ofer middangeard monnum sended

Hail Earendel brightest of angels
Above Middle-earth sent under men

Tolkien wrote "There was something very remote and strange and beautiful behind those words, if I could grasp it, far beyond ancient English." That's all from Wikipedia: here's a more assonantially exact translation:

Hey-there Earendel, angel-the-brightest,
Over Middle-earth men you sent down.

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*On the other hand, this review by R W Chambers adds this: "In the meantime Professor Tupper has become convinced that the so-called First Riddle, which in his edition he passed over as 'demanding no place here,' is in reality an enigma which conceals the name of Cynewulf, and so shows us who is the author of the Riddles. The lot of a convert is seldom an easy one, and Professor Tupper has been in- volved in a good deal of controversy, which is by no means over yet."