Bumpy forehead alien

After Star Trek: The Motion Picture updated the look of the Klingons with a bumpy prosthetic forehead, bumpy forehead aliens became commonplace in Star Trek, since it was an easy way to make human actors look a little bit alien.

Examples

• Klingons
• Talarians
• Cardassians
• Kazon
• Trill (first appearance only)
• Vidians (not noticeable unless they're healthy)