A-LINE or CADO chairs, Steen Østergaard (CADO, 1966)

These are the first chairs I noticed when I first visited Carlos's place, and absolutely loved them... Did anyone ever think we were meant for each other? I think you're right LOL
These are known as the CADO chairs as they were first produced for the CADO firm in Denmark, although at the designer's website they appear as the A-LINE chairs. They were designed by Steen Ostergaard in 1966 and were the first injection moulded in one piece chairs ever and it took only 132 seconds to make one! Oh, and the most important thing: they are as comfortable as beautiful! Østergaard designed different version of this chair (armchair, lounge chair, ottoman) which you can see at pic.2
We've got two in red (you can see one of them on pic.3, which is the one I keep by my side of the bed and is usually covered with layer over layer of pants and shirts... the other one lives at the living room) as well as three in dark green with the upholstered cushion in orange plastic, all of them living “at the other house” (and you can see two of them on pic.4). All of them have a relief stamp behind the seat that reads “CADO. MADE IN DENMARK. DESIGNED BY STEEN OSTERGAARD”.
These chairs have been reissued by the Danish firm Nielaus since 2012, and they're now made in fiberglass reinforced Polyamide (nylon). You can download the brochure in PDF here: http://www.ostergaard-design.com/wp-content/uploads/290_brochure-low.pdf It's got a lot of wonderful pictures!