Agent or participant:
* Assistant
* Applicant
* Servant
* Inhabitant
* Accountant
* Informant
* Consultant
* Tenant
* Opponent
* Participant
Relating to a state or action:
* Relevant
* Important
* Pleasant
* Brilliant
* Instant
* Errant
* Elegant
* Intriguant
* Exuberant
* Radiant
Other:
* Elephant
* Giant
* Infant
* Plant
* Grant
* Aunt
* Cant
* Want
This is just a small sample. There are many more words ending in "-ant", depending on the specific meaning and context.