Palestine is one of just two nations not to be a member of the United Nations, the other being the Vatican City.

North Korea has been a member since the 17th of September, 1991 with their representative being Oh Joon.

Zimbabwe has been a member of the UN since the 25th of August, 1980. Zimbabwe is a "full member" and they have no intention of leaving the organization.

Lastly, Ethiopia has been a member of the United Nations since the very beginning. Ethiopia helped found the UN and has been a member ever since.

Palestine is not on this list due to be recognized as a state, not a country.

More Info: en.m.wikipedia.org