List of Countries Beginning With The Letter O / List of Countries Beginning With The Letter / By Caleb N. List of Countries Beginning With The Letter O (Population in Ascending Order) A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Country Population(2020) Area(Km²) Density(P/Km²) 1 Oman 5,106,626 309,500 16