What is your nation's leader's title?

[Europe and Oceania]

Chancellor/Big Brother.

[Corindia]

President of the Democratic States of Corindia

[New Acardia]

President then there name

[Waldriech]

Mr. Chancellor. (Informal)

The Honorable, Chancellor, Kurt Lammert. (Formal)

His Excellency, Chancellor, Kurt Lammert. (Diplomatic, outside of Waldriech)

[Hiachijan]

High Emperor/Empress of the Hiachijanese Empire.

[Narvatus]

The official title is Executive Councillor, sometimes referred to as Chancellor. Chancellor is never used officially and the incumbent is Kai Alghren.

[Bretagne-Normaundie]

There is two leaders in Bretagne-Normaundie, the Duke and the President. The Duke is a figurehead and symbol of the union between Brittany and Normandy, formed when Normandy entered into a personal union under Brittany in 1023.

[The Land of the Ephyral]

Her Seraphic Illustriousness, Alyrya, First of Her Name, by the Grace of the Immortal Throne, Empress of Messeren, Protectress and Conqueror of the Africanus, Uniter of Iberia, Bastion of Ephyral Ascenda, Defender of the Divine House of Bloodfyre and the Ephyral Peoples.

[Arachaea]

Head of State is President
Head of Government is Prime Minister

Innovative I know.

[Paredonia]

The Head of State of the Federal States is the Monarch. They are usually referred to as 'Your Majesty' and 'Your Grace'. Currently, this position is held by King Aloysius IV, since 1993.

The Head of Government of the Federal States is the Prime Minister. While other countries, such as the United Kingdom, refer to their Prime Minister as 'The Right Honourable', there is no such honourific in the Federal States. Currently, this position is held by Kathryn Greenfield, since 2015.

[Ko-oren]

There are 20 nations in the Union of Ko-oren. The actual leader of all of them is a figurehead, called the President. The real power is with the 20 councillors (one for each nation). However, everything the councillors do, must be passed through a meritocratic 'parliament' consisting of members according to each nation's population, a member of which is called a 'principal'. Each separate nation enjoys autonomy, and their leaders all have different names depending on the sort of nation it is.

Short answer: president.
Long answer: president, councillor, principal, or any of about 10 other terms.

[Auferstanden]

The formal title of the leader of the Socialist People's Republic of Auferstanden is the General Secretary of the Central Committee of the Communist Party of Auferstanden, Chairman of the Presidium of the Supreme State Council of the Socialist People's Republic of Auferstanden and Supreme Commander of the Armed Forces of the Socialist People's Republic of Auferstanden. The informal version, General Secretary, is more commonly used.

[Khorisdorf]

The title of our current monarch is Prince of Mütland.

[Boldara]

High King, while the others are called Kings.

[The Estovakian Greater Federation]

Premier Voychek or General Voychek

[Honiarva]

Pimp-Master General.