The author of the work is the person who actually creates the work.  This person is the one who translates an idea into a fixed, tangible expression that is entitled to copyright protection. 
In some instances, the person may be creating the work as a “Work Made For Hire”.  This means that under certain employment conditions, the actual creator of a work is not the legal author of the work. For works created after January 1, 1978, a distinction was made between employees acting within the scope of their employment and the creation of the work by independent contractors.