Philips of Marnix, Lord of Saint-Aldegonde, Lord of West-Souburg was a Flemish and Dutch writer and statesman, and the probable author of the text of the Dutch national anthem, the Wilhelmus.

"Wilhelmus van Nassouwe", usually known just as "Wilhelmus", is the national anthem of both the Netherlands and its sovereign state, the Kingdom of the Netherlands. It dates back to at least 1572, making it the oldest national anthem in use today, provided that the latter is defined as consisting of both a melody and lyrics. Although "Wilhelmus" was not recognized as the official national anthem until 1932, it has always been popular with parts of the Dutch population and resurfaced on several occasions in the course of Dutch history before gaining its present status. It was also the anthem of the Netherlands Antilles from 1954 to 1964.