Xenobiologist. They study the possible types of alien life we might encounter, or that could exist.
With the letter 'x' or starting with the letter 'x'? Mexico has an 'x'
yodeler
Facer
zoologist
No country in the world begins with the letter X.
Nothing in the kitchen starting with letter X
Quality Inspector is a job. It begins with the letter Q.
x-rayer xylophonist
x-ray
X-Trapolis
Janitor juror
window cleaning