Belgium has produced some really great painters.
Peter Paul Rubens was one of them. He liked to paint chubby people. When someone is described as "Rubenesque", it is a reference to him.
Rene Magritte. Now this guy was a surrealist painter, and frankly, I do think he's awesome, every bit as interesting as Dali. He painted some seriously freaky scary stuff.
And... famous Belgians... Audrey Hepburn. She was born Edda van Heemstra Hepburn-Ruston in Brussels. I think Audrey would probably be the most famous Belgian ever.
Is the fictional character Poirot more famous than Audrey Hepburn? No. But if we're counting fictional and actual people, Poirot might be the second most famous Belgian. But then, most people aren't aware that Audrey Hepburn was Belgian, I suppose, and Poirot is like "look at me, I am the famous Belgian detective Poirot..."