Quiet!
"Xcuse me" and "Xcellent" are interjections that start with the letter X.
'But' is an interjection that begins with the letter 'b'.
Interpolation
Some interjections that start with the letter J include "jeez," "jolly," and "just."
fiddlesticks
"Wow" is an interjection that starts with the letter L.
Kapish is an interjection. It is slang for "Do you understand?"
Q-Tips were an invention. It begins with the letter Q.
The only Scrabble letter that starts with Q is the letter Q.
There are no pronouns in English that start with the letter q.
Kids' items that start with the letter Q are questions, questions, questions.
Yes, almost anything can be an interjection,for instance "DOOM!" could even be one.