A heater is an appliance whose purpose is to generate heat for a building. Heater or Heaters may also refer to:

• Central heating, a system used to heat an entire building

• Aquarium heater, in fishkeeping, used to warm aquarium water
• Boiler or heater, used to heat water for use in a heating system
• Furnace or heater, used to heat buildings using a central system
• Radiator (heating) or heater, used to transmit heat from a boiler
• Space heater, that heats a single area
  • Gas heater, that heats a area using gas
  • Oil heater, that heats oil to heat a room

• Heating element, a device that converts electricity into heat
• Cathode heater, in vacuum tubes and gas-filled tubes
  • Heater, a vacuum tube filament for an indirectly heated cathode in a vacuum tube

• Heaters (band), an American rock band
• "The Heater", a song by The Mutton Birds
• "Heater" (Samim song), a song by Samim
• "Heaters", a song on the IllScarlett album Clearly in Another Fine Mess

• Heater, a slang term for a firearm, usually a handgun or revolver
• Heater (surname)
• Heater shield, a type of shield
• Heaters, West Virginia, an unincorporated community in the US
• A nickname for a fastball