Formal title of your nation's leader?

[Strathy]

The King is normally referred to as 'His Majesty', being addressed as 'Your Majesty' on the first occasion and 'Sir' thereafter. His full title is:

His Majesty Seumas the First of House Uitail of the United Kingdom of Strathy and by the Grace of Almighty God King, Emperor of the Strathan Realms, the Noble the Lord Protector of Partaig, High Marischall of Our Armed Forces, Sovereign of the Most Valiant the Knights of Saint Kentigern, Sovereign of the Worshipful the Knights Precary of Saint Columba, Sovereign of the Most Noble Order of Merit in the Strathan Empire, Defender of the Holy Faith

The Prime Minister's full title is:

First Lord of His Majesty's Treasury, Lord President of the Council, Lord Great Chamberlain, Prime Minister of the United Kingdom, the position being currently held by His Grace the Right Hon. Sir August Maximilian Ellis-Knox KC, Duke of Mealabhaich. As a Duke, he is referred to as 'His Grace' or the 'Lord Duke of Mealabhaich', being addressed as 'Your Grace' or 'My Lord Duke', and thereafter as 'Sir'.

[Azadistan-land of the free]

Sultan of Azadistan,Commander In Chief of the Islamic Azadistani millitary,Keeper of the peace, Defender of Islam, Upholder of Justice,High in chivalry, Trustee of Madinah Al Adalat, Temporary Governor-General Of Thugkoku, Doctor Of Philosophy,
Lieutenant, Guardian Of Islamic Knowledge,Protector Of The Poor and Chairman Of The International Criminal Police Federation.

[Union of the Danube]

The Elected Monarch President of Austria, Hungary, Bohemia, Slovakia, Bosnia, and Serbia under the control of the Union of the Danube.

[Yelenea]

Officially, the Marshal of the Republic of Yelenea, although Prime Minister and Premier are sometimes used, especially internationally.

[Diarcesia]

Depending on the gender, it would be Monarches/Monarchessa Diarcesium (Monarch Diarcesian)

The current Monarch is formally titled as Sandepus Phlegomaeus Etheliscus, Monarches Diarcesium (Sandeep Phlegomy Etheling, Monarch Diarcesian)

[Anwil]

The Honorable Rudolfo DaSilva, Earl of Anvil

[Subhurbia]

Sovereign Adom

[Pauxia]

Our official and formal head of state title is: Prime Chancellor

[Garden at 6th Mile Road]

Stralend en Wonderbaarlijk Licht Koningin Holly Aurora Symantha Vreugde Lavender Astrid Lilac Marlie Nova Radiant Starlight is her full name.

Out of this, Stralend en Wonderbaarlijk Licht Koningin is her title, translates to "Luminous/Bright and Wonderous Light Queen".

[Aeisonia]

President Big Brother
I am paranoid af

[Paradia Eigden]

His Majesty, Ataracian Otat Haiusl Wiedenfel-Casiat Czepiac Koni Jallisberag, Hegen of Paradia-Sur, Berber of Paradia-Nor, Herr of Tolan, Cosaki of Meija, Korig of Para-Vonarcia

[Larin]

Full title (Arabic): القائد الأعلى لخلافة لارين الخليفة عبد الله داود محمد هاغن
Short title (Arabic): الخليفة عبد الله هاغن

Full title (English): The supreme leader of the Caliphate of Larin Caliph Abdullah Dawud Muhammad Haghen
Short title (English): Caliph Abdullah Haghen

[Savannah Soviets]

President of the Savannah Socialist Republic, Commander-in-Chief of the Savannah Defence Forces

[Lillorainen]

President of the Federation of Lillorainen Silas Flemming.

Though, he once made a little joke of the fact that monarchs and other noblemen/noblewomen often have painfully long names and titles - so he gave himself a fancy title too (which he, of course, doesn't officially use):
Silas Vestergaard Flemming, Highly well-born to Longenager; President of the Federation of Lillorainen; Descendant Unifier of Lillamala, Lillöer, Polypolia, Serböer, Terra Bianca, Rathland, Rigesöer, Vedjading, and Visholm; Supreme Commander of the Lillorainian Armed Forces; Defender and Unifier of the Lillorainian Culture throughout the Pacific, the World, and the Multiverse; Defender of National Freedom; Presider of the Meritocratic Unity Party, honorably chosen by girlish fights; State Councilor of the Rathland; Federal Regional Planning Commissioner; Master of Science of the Pontrath University; Off-Duty Commander of the Kirajevo Army Base; Beer King of Jillich, Lysköping, and Melapolis; Supreme Destroyer of the National Rum Reserves.

[Kowani]

Short Title (English): High Leader of Kowani, Hijo D’Cadela
Short Title (Kowani): Olider mâlto d’Kowani, Hijo D’Cadela

Long Title (English): High Leader of Kowani and all it encompasses, King of Spain and Portugal, Unifier of The Iberian Crowns, Heir to the Caliphate of Al-Andalus, First Citizen of Kowani and foremost protector of the people, Hijo D’Cadela
Long Title (Kowani): Olider mâlto d’Kowani e tudo q’contenga, unificador dôscoronas ibéricas, Rei Do’panna e Portugal, Eredero dôcalifato dâlandalus, ciudadano primiero d’Kowani e primer protector dâgente.

[Greater Canadian States]

The Formal title of the Greater Canadian States is Supreme Emperor .

[Estado Novo Portugues]

Head of state: Sua Santidade, Bispo da Lisboa (His Holiness, Bishop of Lisbon)
Head of government: Sua Excelência Católica, Primeiro Ministro do Estado Pontifício (His Catholic Excellency, Prime Minister of the Ecclesiastical State)

[Pan-Asiatic States]

Secretary-General, or Supremo. The former is much more, well, formal; whilst the latter is more archaic. It's like "President" and "Sir".

Another, much more complete, title, though almost never used these days; is Hari ng Mga Katagalugan- wherein the Katagalugan refers to The Tagalog People.

[Austria Minor]

Her majesty, Lady Diane Hiffelm IV Of The Defant family, and Jarutk family. Thirteenth in line for the throne of Italy, France, America, Spain, England, Hungary, Bohemia, Moravia, And Bosnia. Also 2nd in line for the throne Of Herzegovina, Poland, Germany, Switerzland, Sudan, Egypt, Algeria, Corsica, And Sardinia. Currently the grand duchess of Cambridge, Wellington, Essex, Wessex, Maine, Massachusetts, Maryland, Sicily, Verona, And first in the line for the Holy Roman Emperor’s throne of Germany. However we mostly call her M’lady formally or Madame.

[The Fist of Justice]

Elisabeth Leibensperger, Lady of Death and the Eternal Ruler over the Land and Peoples of Justicia.

Shortened: The Eternal Lady. Servants and lesser beings call Her "My lady" or "Her holiness"

[Pan-Asiatic States]

Her majesty, Lady Diane Hiffelm IV Of The Defant family, and Jarutk family. Thirteenth in line for the throne of Italy, France, America, Spain, England, Hungary, Bohemia, Moravia, And Bosnia. Also 2nd in line for the throne Of Herzegovina, Poland, Germany, Switerzland, Sudan, Egypt, Algeria, Corsica, And Sardinia. Currently the grand duchess of Cambridge, Wellington, Essex, Wessex, Maine, Massachusetts, Maryland, Sicily, Verona, And first in the line for the Holy Roman Emperor’s throne of Germany. However we mostly call her M’lady formally or Madame.

Daaaaaaaaaaaaaaaaaaaaaang..

[Austria Minor]

Her majesty, Lady Diane Hiffelm IV Of The Defant family, and Jarutk family. Thirteenth in line for the throne of Italy, France, America, Spain, England, Hungary, Bohemia, Moravia, And Bosnia. Also 2nd in line for the throne Of Herzegovina, Poland, Germany, Switerzland, Sudan, Egypt, Algeria, Corsica, And Sardinia. Currently the grand duchess of Cambridge, Wellington, Essex, Wessex, Maine, Massachusetts, Maryland, Sicily, Verona, And first in the line for the Holy Roman Emperor’s throne of Germany. However we mostly call her M’lady formally or Madame.

Daaaaaaaaaaaaaaaaaaaaaang..

What? Austria Minor has had a few conquest in her days before but now were crumbling!

[Weiskuste]

Prime Minister Pietro Maaren

[Carlist Peru]

His Royal and Loyal Viceroy Gomez de Cañete, Governor of Peru and Alto Peru, General of the Peruvian Armies, Grand Admiral of the Peruvian Navy.

[Commonwealth Republic of Andyrssia]

The head of state and government is the Premier of the Assembly and People of the Commonwealth Republic, colloquially known as just the “Premier”. Formally he/she is to be addressed as “Your Excellency”, and informally as “Mr./Madame Premier”. The office is currently held by Andrew Bonanimo.