Henri Cassiers is a Flemish artist who was born in 1851 in Antwerp. He studied to become an architect and besides that he followed an art course at academies in Brussels and Sint-Joost-ten-Node. Early on he created his own style inspired by Dutch traditional costumes, village views and Maritimes scenes. He is known for his applied art, for instance illustrations, posters, wallpapers and picture cards.

Cassiers illustrated several magazines, such as Le Globe Illustré, De Vlaamsche Patriot and L'Illustration Européenne. Moreover he illustrated various books from Emile Verhaeren, Camille Mauclair and Jean d'Ardenne. Furthermore Cassiers got a lot of request from the shipping industry to make advertisements. He is best known for his poster for the Red Star Line.

Together with Jan Toorop, Achille Chainaye and François-Joseph Halkett and others Cassiers was part of Les Hydrophilles, an art group from Brussels. With this group they have had five exhibitions.