Dynamic Entity Reference
Overview
Dynamic Entity Reference provides a field type/widget/formatter combination for Drupal 8 that allows an entity-reference field to reference more than one entity type.
Features
Create a single field to hold references to Users and Nodes. Or Terms and Nodes, or all three.
Requirements
Field
Known problems
Please use the issue queue to report problems.
Credits
Development being undertaken by @larowlan of PreviousNext and @jibran