An officiant is someone who is authorized to perform religious ceremonies. The officiant may have a specific title.

In the US the word ‘celebrant' is often used interchangeably with the word ‘officiant', however, there is a slight difference!

An officiant refers to an individual – a priest or minister, for example – acting in a religious capacity.  A celebrant is someone authorized to officiate a wedding ceremony that may or may not be religious (i.e. civil).

Subtle…but different. 😉

Merriam-Webster Online Dictionary
officiant (noun)
one (as a priest) that at a religious rite - officiates
« View Entire Wedding Glossary