Deserter

wiktionary

ref

Borrowed from Latin desertor(“deserter”), from desero(“I forsake, I abandon”); or from desert +‎ -er.

etymonline

ref

deserter (n.)

"one who forsakes cause, duty, party, or friends," 1630s, agent noun from desert (v.). Especially "soldier or sailor who departs from position without leave and without intent to return" (1660s).