I have a roster list which has First Name, Last Name, Name, User ID and Email among other pieces of information.
I want to create a workflow which does a lookup from a current list which shows Name (lookup field) to the Roster and pull the User ID field to populate a people picker field in the current list.
Is this possible using Nintex Workflow 2016?
if I got your requirement correctly, you do not need a workflow for that.
you can configure Name lookup list field to bring in further columns from roster list into 'current' list