The Netherlands were neutral.
Switzrland, Spain, The Netherlands, Denmark
The Netherlands proclaimed it's neutrality during World War I, and their neutrality was respected. It also proclaimed itself neutral during World War II, but a little detail like that didn't bother Hitler. He invaded The Netherlands anyway.
Netherlands, Belgium, Luxembourg, Denmark
2 countries, Switzerland, Netherlands
Spain, Sweden, Norway, the Netherlands and Switzerland.
During World War I, the notable neutral nations were Spain, Sweden, Norway, Switzerland and the Netherlands.
Switzerland, Netherlands(holland), Portugal
Switzerland, and Netherlands were neutral during world war 2
Switzerland, Argentina, Sweden, and The Netherlands were all neutral. However, Switzerland is probably the most famous neutral nation, due to its location in Central Europe, making its neutrality difficult to maintain.
Switzerland remained neutral because it was largely inaccessible - very difficult to attack and occupy. Netherlands and Belgium remained neutral for the opposite reason - they were too accessible from either side.
Spain, Norway, Sweden, Denmark, Switzerland, the Netherlands and Albania where all neutral during WW1