General synonyms:
* Runaway
* Escapee
* Outlaw
* Evasive
* On the lam (informal)
More specific synonyms:
* Deserter (if referring to someone who has abandoned military service)
* Convicted felon (if referring to someone who is evading the law after being convicted of a crime)
* Person of interest (if referring to someone suspected of a crime)
* Missing person (if referring to someone who has disappeared without a trace)
The best synonym to use will depend on the specific situation and the intended meaning.