|This article is about the character in The Lady of the Lake. For the game character in The Witcher, see Kobus de Vollen.|
|'Hooray!' he yelled, waving his mace. 'Redania! Redania is coming! Eagles! Eagles!'|
|- Kobus de Ruyter during the Battle of Brenna, The Lady of the Lake|
Kobus (d. March 1268), the ninth Count de Ruyter, was a Redanian noble and commander who led the Tretogor forces in the Battle of Brenna. He was killed by a crossbow bolt, during a desperate charge against the Nilfgaardian "Venendal" division which prevented it from reorganizing in time to face the flanking attack of Blenheim Blenckert's forces. He was 56, at the time of his death.
- Several other de Ruyter's are mentioned in the series, including Count de Ruyter, father of Joanna, Jolanta and Julia, and Ambassador de Ruyter. It is unknown what relation Kobus was to the other members of the de Ruyter lineage.
- In The Witcher, it's noted one of the pieces of armor needed to craft Raven's armor belonged to de Ruyter.
- In The Witcher 2: Assassins of Kings, during Chapter II, Yarpen Zigrin mentions de Ruyter when reminiscing about the Battle of Brenna.
- Michiel de Ruyter was a Dutch admiral most noted for his achievements with the Dutch Navy during the Anglo-Dutch Wars.