The River Queen

The River Queen or  'Malkia Wa Mto' in Swahili.
 
“The River Queen, part mer, part river-spirit, could summon far worse, they said. Possibly wash away all of Lunathion, if provoked. She was a daughter of Ogenas, according to legend, born from the mighty river-that-encircles-the-world, and sister to the Ocean Queen, the reclusive ruler of the five great seas of Midgard.” – Sarah J. Maas