The PIC16F84 is a microcontroller in the PIC family of controllers, produced by Microchip Technology. It is an improved version of the PIC16C84, and almost completely compatible, with better program security and using flash memory instead of EEPROM memory for program memory. Both versions feature a wide voltage range, low power consumption, internal timer, and PIC I/O controls.

The PIC16F84 is popular in many hobbyist applications, the PIC16C84 was the first PIC microcontroller to feature a serial programming algorithm and flash memory, both of which lend themselves to hobby use: only a simple and cheap programmer is required to program, erase and reprogram the chip.

The microcontroller is a member of Microchip's 14-bit series (the instruction word size is 14 bits for all instructions), making the '84 a good development prototype for other similar but cheaper one-time-programmable 14-bit devices.

Its easy programmability and good availability also made it a favourite for various 3rd party after-market additions to consumer electronics, such as PS2 'chipping' modifications (used to allow the use of imported or pirated games), and satellite/cable decoder box cards for similar purposes. (These usages may be illegal in some countries).

The '84 is being at least partly replaced for hobby use by the PIC16F877 which also features In-Circuit-Debugging, self-programming ability, 3 timers, PWM output, capture/compare input, a 10-bit analogue-to-digital converter, various serial input and output peripherals and a parallel slave port.