An executor is a legal person (this can include a trust corporation) who carries out the wishes of a person who has died, and is appointed by a Will. If the executor is female, then they may be called an executrix. If all executors are female, then they may be called executrices.
If there is no will, then the people who do the same job as executors can only take authority by order of the court. They are called the Personal Administrators of the estate.
In both cases, collectively Executors and Personal Administrators can be called Personal Representatives (“PRs”).
Sometimes, the Executors of an estate look after assets for others in the longer term. In this case, they can also have the role of Trustees.