Viridian

Viridian is the main antagonist in the book The Letter for the King, it's sequel The Secrets of the Wild Wood, and it's Netflix series with the same name as the former.

In the Netflix series he is played by.

The Letter for the King
Viridian is the younger son of the King of Unauwen. His older twin brother Prince Iridian is the heir to the throne and will one day become King of Unauwen. In the Eviellan wars Viridian conquers some of his father's land as well as some of neighbouring kingdom Dagonaut's lands. Viridian now rules Eviellan (in the south) and becomes King in his own right. He also partially conquered Deltaland. He disguises himself as the Black Knight with the Red Shield, leader of the Red Riders. He is wondering in a forest in the Kingdom of Dagonaut when he sees Sir Edwinem of Forèstèrra (the Black Knight). He challenges Edwinem to a fair duel to the death, and Edwinem accepts. Viridian then goes against his oath and murders Edwinem. Edwinem was carrying an important letter for the King of Unauwen. Edwinem's squire Vokia goes to a nearby chapel and gives Tiuri the letter. Viridian will do anything to stop the letter getting to the King. For the rest of the first book he is more of an overarching antagonist, with people like Jaro, Slither and the Mayor of Dangria doing his dirty work.

The Secrets of the Wild Wood
The letter gets to King Unauwen. The letter was the catalyst for the armies of both the King of Unauwen and the King of Dagonaut to fight against the army of Viridian, King of Eviellen. Viridian’s army retreats back to their kingdom. Viridian then challenges his brother to a fair duel. Iridian accepts and ends up killing Viridian. Little did Iridian know but Viridian used the Weapon of Woe (a poisoned sword), and so, Iridian then dies also. Iridian’s son later is crowned heir to the throne.

Netflix Series
Viridian appears in three out of the six episodes, being "Storm Clouds Gather", "Spiral", and "When the Blood Moon Rises". Differences between the series and the books include the King of Unauwen is given the name Favian and in the final duel Iridian survives. After the knighting ceremony of Foldo, Arman, Piak, and Tiuri, a flock of birds formed Viridian's face.