Belgian designers  

Not a soul...
😉

Lots
of world class fashion desisgners..all who came out of one school at Antwerp.
Other than that I can only think of Maarten Van Severen
& Henry Van De Velde

I
I found this, which has some great stuff
http://www.behive.be/design/furniture/

This lounge is exceptional...
if it is stable.

I also like this very much this canopy...
for reasons I only partly explain.
I've always been a sucker for four posters with canopies; this updates the canopy bed in a modern form language. And I just really like the form. It would even look great out on my patio. But can it duplicate the amorous functionality of the posts without further modification? 🙂

Mid century?
His work as a furniture designer, architect and founder of two major schools, his choice to name Walter Gropius as his successor in Weimar and his role in the famous Werkbund debate in Köln certainly put Henri Van De Velde up there somewhere among the founding fathers. Maarten Van Seeveren successes with Vitra and the likes also give him a prominent place among the end-of century designers, but neither one would qualify for Mid Century Modern?.
Design in the DA-forum context is mostly furniture and lighting.
As far as those areas are concerned furniture has been far more important than lighting. Major lighting companies with well designed products are a rather recent development in Belgium. So?furniture. I think that the following names are worth attention. None of them were major innovators, but good to very good designers within the modernist movement.
Marcel-Louis Baugniet motsly known for his paintings did some intersting furniture around 1935 that certainly qualifies for modern, later one Gaston Eysselinck and Jules Wabbes designed very much in the tubular Breuer/MvdRohe style.Few years later, Willy Van Der Meeren for Tubax, Alfred Hendrickx for Belform, Jos De Mey for Van den Berge Pauvers, Emiel Veranneman as well as Philippe Neerman and Willy Nel for De Coene.(both were co-inventors and patent holders of the screw-through-bushing that is now highly identified as one of IKEA?s trademark connections)typically designed for a few avant garde furniture manufacturers.
The architects Renaat Bream, Lucien Kroll and Charles Vandenhove have done some interesting work to.

My
Mistake..he just sprung to mind as an eminent Belgian designer..(I didn't register the 'MCM' in the question
I saw a beautiful table by a Belgian female designer recently too
Let me go and see if I can find it

Found It!
Wel, I assume it is a female ??
http://www.gabrieleheidtmann.de/new/15.php

Found it!
Koen, you're a genius. While searching under Gaston Eysselinck's name, I found his exhibition in the Design Museum Gent. While scrolling through their other exhibitions, I found a collection called "100 Years of Demeyere", a Belgian company that makes stainless cookware. I went to their website and there was a much newer but still unmistakably the same manufacturer tea kettle. Here's a picture of the new kettle still available. Thank you!
http://www.demeyere.be/

Hi Riki
I am glad you found it. I would like to help you with the name of the designer, but I do not know it myself. As you have noticed in the Demeyere website designer's names are not always mentioned. John Pawson is of course for the line that is called Pawson, I did the Atlantis (not mentioned) and Sirocco (mentioned)line but over and beyond Pawson and Sirocco, designers are not mentioned. But if you want to know I am sure they will answer your question.
Dear Robert,
Yes Marleen is female!

My kettle
This is my first attempt to post a personal picture. Here goes.

Riki--
You totally BLEW a golden opportunity to treat us to a little reflect-o-porn*.
*see below
http://www.snopes.com/photos/risque/kettle.asp

.

Sacrilege
I cannot believe you have attributed my beautiful teapot to Gianni Saccheco di Frutta. He is so not Belgian. Bulging, yes. Belgian, no.