What are the different types of W-series forms?

Form W-8BEN, Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding (for Non-US Individuals)
Form W-8BEN-E, Certificate of Status of Beneficial Owner for United States Tax Withholding and Reporting (Entities) (for Non-US Legal Entities)
Form W-8ECI, Certificate of Foreign Person's Claim That Income Is Effectively Connected With the Conduct of a Trade or Business in the United States
Form W-8EXP, Certificate of Foreign Government or Other Foreign Organization for United States Tax Withholding
Form W-8IMY, Certificate of Foreign Intermediary, Foreign Flow-Through Entity, or Certain U.S. Branches for United States Tax Withholding (for Intermediaries – Financial institutions/Banks)
Form W-9, Request for Taxpayer Identification Number (TIN) and Certification (for US Persons).