One-Letter Name/Quotes

Yumi: "D-san, I finally get it... the D is for "Dream"!
Horis: Then what's J's J?
Hikaru: Maybe it's Japan.
Izumi: It's the J in "joke".
Guy: Judgment... or maybe, Justice?
Soldat J: (I don't know either...)

—Characters speculating on One Letter Names, Super Robot Wars W

Isaac Washington:"You ever gonna tell anyone what the fuckin' G stands for?"
Agent G:"...No."

—One of many questions asked about G's name in House of the Dead: OVERKILL

Rock: I know! We can call the future Zero just 'Z'!
Bass: 'Z'? That's a letter, not a name! ...er...no offense, X...
X: None taken, I guess...

—Epilogue (fanfic)

T.J.: So, can I ask what the E stands for?
Mr. E: No.
T.J.: You are so cool.

—Recess

General Specific: I don't want an "X Agent"! I want a current agent!
Private Public: The "X" is put in to indicate mysteriousness rather than his job status sir.
General Specific: Well why can't he choose another letter? Like "K"?
Private Public: "K" isn't as mysterious a letter as "X", sir.
General Specific: What about "L"? "L" is prety mysterious! *waving fingers* Llllllllllllll... Lllllllll!!!

—Sheep in The Big City