The Project Executive (PE) is a role in projX and Prince2 methodologies. The PE, as the senior member of the Project Board, is responsible for the successful completion of the project and achievement of the benefits. The PE appoints all members of the project, directly or delegated, and is the final voice for any decision.
Through the course of the project the PE consults the Senior User and Senior Supplier on important decisions, but the project is run as a dictatorship, not a democracy, and therefore the PE can override and overrule any decision.
The Project Sponsor is commonly understood as the individual who provides funding to the project and by extension has ultimate decision making authority on the project.
While other terms for this role are inconsistency used, other roles with similar characteristics may be Project Owner, Project Champion and similar titles.