Yes.
To quote from The Road of Kings (and Return to the Road of Kings): "King Moranthes II, a weak, effeminate ruler who relied upon his strongest barons for support, double-crossed the ruler of Khoraja and captured him, holding for ransom and threatening to sell him to Koth. He also captured his own wife, Queen Marala, for lewd behaviour among his courtiers during an absence. He also sold his daughter, Olivia, into slavery for refusing to marry a prince of Koth. The following king, Amalrus, betrayed Ophir's ally, Aquilonia, and sided with Koth against that great nation, capturing King Conan and sending troops into Conan's realm. He also was a weak king, for his brother fought for his right to the crown, holding the eastern half of the kingdom. The current king of Ophir, Ludovic, is an Aquilonian vassal-king, subject to King Conan."
King Moranthes II, IIRC, was established by L. Sprague de Camp in the story "The Star of Khorala." However, he ruled pre-Conan the King, so he doesn't really answer your question.
King Amalrus was established by Robert E. Howard in the story, The Scarlet Citadel. He was killed by Prospero at the end of that story. He is definitely part of canon. (I would presume Amalrus' brother would try to take the throne at this point.)
King Ludovic was established by L. Sprague de Camp in one of the stories found in Conan of Aquilonia (Black Sphinx of Nebthu, IIRC). Whether he is canon or not depends on what you accept as canon. Conan set Ludovic up as a vassal king. Ludovic may be the brother of the former king, or he could be an Aquilonian noble Conan gave the throne to.
