There is only one major type that is missed in the list and that is the Flat 12 configuration…
There are a number of influential Ferrari’s that use this engine configuration and they’ve sold in higher numbers than the Bugatti Veyron!
Please don’t forget this amazing engine type as they were well known for being smooth, hard revving and amazing to listen to! 
technicly it’s a 180° V, not an actual opposite
The Bugatti Veyron has a W16 engine?
Yes, it does. It is basically two W8 Audi engines glued on.
yup, exactly that, VAG group only uses those, they have W8, 12 and 16
They used to do them, in the early 2000s. Their new engines are now Vs, I am thinking about the new 4.0 V8 twin-turbo, however the W12 and W16 are still on production since then.
Well… the W16 is just some VR4 or VR8 thrown together 