What is End User?

Legal Definition
In product development, an end user (sometimes end-user) is a person who ultimately uses or is intended to ultimately use a product. The end user stands in contrast to users who support or maintain the product, such as sysops, system administrators, database administrators, information technology experts, software professionals and computer technicians. End users typically do not possess the technical understanding or skill of the product designers, a fact that is easy for designers to forget or overlook, leading to features with which the customer is dissatisfied. In information technology, end users are not "customers" in the usual sense—they are typically employees of the customer. For example, if a large retail corporation buys a software package for its employees to use, even though the large retail corporation was the "customer" which purchased the software, the end users are the employees of the company who will use the software at work.

Certain American defense-related products and information require export approval from the United States Government under the ITAR and EAR. In order to obtain a license to export, the exporter must specify both the end user and end use using an end-user certificate. In End-User License Agreements (EULAs), the end user is distinguished from the value-added reseller that installs the software or the organization that purchases and manages the software. In the UK, there exist documents that accompany licenses for products named End user undertaking (EUU).
-- Wikipedia
Legal Definition
Actual person who uses a deliverable, be it a product or a system or a process. Contrasts to those who authorize, manage, build and deliver the deliverable.