Note: I'm talking monarchs here...
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
And I'm using Harald V of Norway as my starting point for this post.
Harald of Norway and Albert of Belgium are first cousins - their mothers (Crown Princess Märtha and Queen Astrid were sisters).
Harald and Margrethe are second cousins - their grandfathers Haakon VII and Christian X were brothers. In addition, they're also second cousins another way, as Harald's grandmother, Princess Ingeborg of Sweden, was a sister to Haakon and Christian. This also means that Albert of Belgium also is a second cousin to the Danish monarch, as he and Harald share Ingeborg as a mutual grandmother.
Harald and Elizabeth II are also second cousins as Harald's grandmother, Maud, was a sister to Elizabeth's grandfather, George.
Harald and Constantine (and therefore also Sofia), are third cousins by way of Christian X, and also by way of Queen Victoria. I'm doing a genealogy project, and without being nearly half way done or anything, Harald and Constantine are related in at least seven different ways. Mutual ancestors include Christian X (3rd cousins), Queen Victoria (3rd cousins), Friedrich Wilhelm III of Prussia (4th cousins once removed), Christian Albrecht of Gottorp (8th cousins once removed), Friedrich II of Hesse (6th cousins), Frederik 5 of Denmark (half 6th cousins), and Frederik 2 of Denmark (11th cousins once removed)
Harald and Ernst August of Hannover are also 3rd cousins.
As are Harald and Juan Carlos of Spain.
Harald and Carl Gustaf of Sweden are 2. cousins once removed (Oscar II of Sweden), 3rd cousins (Queen Victoria), 4th cousins (Wilhelm of Schleswig Holstein Beck Glucksburg) 5th cousins (Friederich Wilhelm III of Prussia), 10th cousins (Frederik 3 of Denmark) and 12 cousins once removed (Christian 3 of Denmark)
Harald and Beatrix are 4th cousins once removed.