It marks the spot
From the last it is third
But for x-ray
It starts almost no words.

Expunges
Expires
Examines
Extolls

Elixir, a mixer
Ex post facto.

In both cases it looks the same
Like Cousin C
It’s a cross only not straight up
Like Cousin T.

Explaining
Exerting
Expatriating

Extant, exacting
Exasperating

There’s no alphabet king
No one “Letter Rex”
But in Alphabetowne
There’s no one quite like X