Complex sentence: Huan, also known as "the Hound of Valinor", was a great hound, approximately the same size as a small horse, given to Celegorm, one of the Sons of Fëanor, by the Vala Oromë the Hunter.
Split into simpler sentences: Huan, also known as "the Hound of Valinor", was a great hound. Huan was given to Celegorm, one of the Sons of Fëanor, by the Vala Oromë the Hunter.