In the Lord Darcy stories, the current King of the Angevin Empire and
Emperor of the Holy Roman Empire is titled

    John IV, by the grace of God, King of England, of France, of Scotland,
    and of Ireland, Emperor of the Romans and the Germans, Premier Chief of
    the Moqtessumid Clan, Son of the Son, Count of Anjou and Maine, Prince
    Donator of the Sovereign Order of St. John of Jerusalem, Sovereign of
    the Most Ancient Order of the Round Table, of the Order of the Leopard,
    of the Order of the Lily, Lord and Protector of the Western Continents
    of New England and New France, Defender of the Faith.

It's fairly obvious that some of these titles were accreted as a result of
conquests and treaties suborning political entities to the Angevins.

What titles might the Emperor of the Third Imperium have accreted? Would
some of them pre-date the Third Imperium in actuality?

Some of the titles I imagine the Emperor might hold:

*Canonically, Emperor of the Third Imperium
President of the Senate of the Sylean Federation
King in the Chanestin Worlds
Ishimkarun to the Vilani Peoples (possibly in Vilani as "Ishimkarun
    Bilanidin")
Secretary General of the Terran Confederation (NOTE: The head of the
    Solomani Confederation probably also claims this title. So what? Both
    the Emperors of the Eastern and Western Roman Empires claimed to be the
    representative before G-d of the Senate and the People of Rome...)
Protector of Terra ("Inherited" from the Emperors of the Rule of Man)
*Canonically, Archduke of Sylea
*Canonically, Marquis of Usdiki
Sovereign of the (Imperium-wide orders listed on
https://wiki.travellerrpg.com/Knight)
Sovereign of the (Domain of Sylea orders listed on that same page)

Any "cultural region" that has a history of being an interstellar polity
probably also has a title that accreted to the Emperor when the worlds of
the polity/cultural region acceded to the Third Imperium.

Thoughts? Discussion?

®Traveller is a registered trademark of
Far Future Enterprises, 1977-2022. Use of
the trademark in this notice and in the
referenced materials is not intended to
infringe or devalue the trademark.

--
Jeff Zeitlin, Editor
Freelance Traveller
    The Electronic Fan-Supported Traveller® Resource
xxxxxx@freelancetraveller.com
http://www.freelancetraveller.com

Freelance Traveller extends its thanks to the following
enterprises for hosting services:

onCloud/CyberWeb Enterprises (http://www.oncloud.io)
The Traveller Downport (http://www.downport.com)