Rex (Latin for "King") is the name of several things.

• The Rex parade is a Carnival Krewe in New Orleans.
• Rex (band) is a Dream pop alternative rock band.
• Rex (company) is an Italian company that makes electronics, mechanics.
• Rex (ship) was an Italian luxury ship, sunk by allies bombers at Slovenian coast in 1944
• The Rex series of PDAs, including the REX 5000 and REX 6000.
• The Cornish Rex and the Devon Rex, cat breeds.
• Rex was the original name of the Rexx programming language
• rex (Regional Express) is a budget airline that services the Eastern states of Australia.
• Metal Gear REX from Metal Gear Solid.
• REX (short for WRX)