For places:
* Infest: This implies a persistent presence that is unwelcome or harmful.
* Plague: Similar to "infest" but often suggests a more intense or overwhelming presence.
* Lurk: This suggests a hidden, stealthy presence.
* Shadow: This implies a dark or ominous presence.
* Loiter: This implies a lingering presence in a place.
* Frequen: This suggests a regular or habitual presence in a place.
For thoughts or feelings:
* Troubles: This suggests a persistent worry or anxiety.
* Preoccupy: This implies that a thought or feeling is constantly on one's mind.
* Pursue: This suggests that a thought or feeling is being chased or followed.
* Dog: This implies that a thought or feeling is persistently bothering someone.
* Pester: This suggests that a thought or feeling is annoying or irritating.
For ghosts or spirits:
* Visit: This suggests a brief appearance or presence.
* Appear: This implies a visible presence.
* Hover: This suggests a ghostly presence that is suspended in the air.
The best synonym for "haunt" will depend on the specific context of its use.