The name Kellen is a boy's name of German, Irish origin meaning "swamp; slender". Kellen is ranked #622 on our popularity charts and is often added to lists like Boy Baby Names Moving Up Fast and discussed in our forums with posts like "Sibset makeover game! B/G pairs".
From the experts:
Kellen is German in origin and Irish in spirit. Kellen has fallen a bit in popularity for boys since its peak in 2012, but it has possibilities for girls too. In fact, Kellen's similarity to such feminine names as Helen, Ellen, and Kelly might make it a tough one for a little boy to carry, though the macho image of Twilight actor Kellan Lutz will help with that.