P is for psycho
T is for tzar
C is for chevron
G is for gnat
H is for honesty
J is for jalapeno
K is for knave
M is for mnemonic
O is for opossum
V is for verklempt
W is for wunderkind
Any others?
C is also for czar
X is for xenophobia
L is for Llanelli
A is for aisle, B is for bdellium.
H is for hour and heir
H is for humble and herb if you’re a Yank
H is for hotel if you’re an old-fashioned posh Brit
D is for Djenné, Djibouti, and Djakarta
E is for Eammon
The O in opossum is pronounced, quite clearly. Sure, lots of people say “'possum,” but that is a different word, a slangy version of the animal’s true name, and written without the O (sometimes, though not necessarily, with an apostrophe to indicate its absence).
Most of your examples seem to be of initial silent letters, but some are just ones sounded a bit differently from usual, so I am not quite sure what you are getting at here.
I’m basically seeking examples of what to say when spelling words by letter over the phone, for the sake of utterly confusing the other person. 
Some people actually say the “O” in opossum? Never once have I heard it pronounced that way!
A as in Aaay!
B as in Bee
G as in Gee
J as in Jay
K as in Kay
O as in Oh
P as in Pee
Q as in Que
T as in Tee
Moving from IMHO to Game Room.
You mean Q as in Queue?
O is for Oeconomics
Q is for Quay
Then Opossum, Verklempt, and Wunderkind make no sense, since the first letter is pronounced exactly as you would imagine.
Only if you speak German. 
Looks like there’s two separate themes developing. First (which was my OP’s intent) there’s the deceptive:
A is for “Arr, Matey!”
E is for eye, ell, err
S is for sea
Y is for you
Second, less deceptive but equally confusing:
B as in Bea
D as in Dee
E as in “Eeeee!”
P as in pea
T as in tea
Z as in zed
Similarly D is for (Carreg-y-) Ddafad, but that’s cheating. Actually, so is “Llanelli” technically, because “ll” is one letter in Welsh, just like “dd”.
A for horses
B for Mutton?
C for yourself
D for dumb
E for brick
F for vescent
etc
The Barenaked Ladies on their kid’s album has an awesome song about such words. Crazy ABCs Make sure you pay attention to the order of the alphabet as it wasn’t until it was released as a CD that anyone commented/noticed it was wrong. But a great song. If you like that song, you’ll love their Ninjas song and 7 8 9 too!
P as in “pneumatic” (at least, as it is pronounced now).
I used to work at a call center where we had two servers, P and T. About once a week, the servers would crash, and everyone would have to switch to one server. This meant someone yelling out, “switch to P as in Paul!” or “T as in Tom!” So of course, being the troublemaker I am, I had to start yelling out “P as in Pterodactyl!”
A as in Fuckin A
I have one of these lists too! I use it to sometimes mess with friendly vendors when naming off serial numbers
A - Aegis
B - Bdellium
C - Czar
D - Djinn
E - Eye
F - Fjord
G - Gnaw
H - Hour
I - Is
J - Junta
K - Know
L -
M - Mnemonic
N - Nguyen
O - Oedipal
P - Phonetic
Q -
R -
S - See
T - Tsar
U - Urn
V -
W - Wrench
X - Xenomorph
Y - Yggdrasil
Z -
I can’t believe I didn’t have this one based on the thread title:
M is for Murderousness