Out of doubt, out of dark, to the day's rising
he rode singing in the sun, sword unsheathing.
Hope he rekindled, and in hope ended;
over death, over dread, over doom lifted
out of loss, out of life, unto long glory.
But Merry stood at the foot of the green mound, and he wept, and when the song was ended he arose and cried:
'Théoden King, Théoden King! Farewell! As a father you were to me, for a little while. Farewell!'
As many fans of Tolkien are perfectly well aware, the personal names of the kings of Rohan are all Old English words for king or ruler, or for an attribute that would be valued in a king in a more violent time.
Brego -- a leader, governor, prince
Aldor -- a chief or prince
Fréa -- a lord or master
Fréawine -- from Fréa plus wine, a 'dear or beloved lord.'
Goldwine -- a generous and kindly prince.
Déor -- 'brave, bold, as a wild beast.' Cf. Lionheart
Gram -- 'furious, fierce.'
Helm -- a helm, poetically used of a king who protects his people like a helmet.
Fréaláf -- Fréa, 'lord', 'master', plus láf, 'what is left, remnant.' Since both of Helm's sons had perished, he was succeeded by Fréaláf, his sister's son.
Brytta -- 'bestower, distributor, prince.'
Walda -- 'ruler'. See also here.
Folca -- from folc, 'people, folk;' in the form 'folca,' meaning 'of the people.'
Folcwine -- from folc plus wine, meaning 'friend of the people.'
Fengel -- 'prince.'
Thengel -- 'prince.'
Théoden -- 'prince, king.'
That's rather a lot of words for king or prince, no? Tolkien is obviously having a bit of philological fun, but a couple of points are worth making. First, although nearly every one of the words for ruler listed above appears in Beowulf, one of the most common in this -- for Tolkien -- poem of poems is entirely absent, drihten, which is also an important term, even in Beowulf, for God, i,e, 'the Lord.' This suggests that Tolkien was not just haphazardly converting words into names. (As if that would ever happen.) Which brings me to my second point. Given this, was Tolkien perhaps taking a cue from the history of another name that became a title? Caesar, as we know, became both kaiser and czar. Did the names of the kings of his beloved Rohirrim become titles in the same way? Was it part of Théoden King's 'long glory' that his name outlived his memory and became synonymous with king?