You may want to narrow down your criteria a good bit. The question is much too broad, as several countries were not members of NATO in the 1950s - some of those countries later became members of NATO, some were in the Warsaw Pact in the 1950s (some of those, too, would eventually become members of NATO), some countries were unaligned.
Greece, Turkey, West Germany, Spain, Czech Republic, Hungary, Poland, Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia, Slovenia, Albania and Croatia.
Bangladesh
The Netherlands is a founding member of NATO.
No, Romania was part of the Soviet bloc when NATO was founded in 1949.
Luxembourg was a founding member of NATO and joined on April 4, 1949.
No, Iraq is not a member country of NATO, but NATO does have a special partnership with Iraq.
Belarus is not a member country of NATO.
The United Kingdom was one of the founding members of NATO in 1949 and has remained a member state ever since.
Unless I am mistaken Turkey is a member of Nato.....
Turkey. However, Turkey remains a member of NATO and a candidate for the European Union.
The member nations of NATO agreed to come to the aid of any country that was under attack.
Turkey
Spain