C4, C04, C.IV, C-4, or C-04 may refer to: Places Caldwell 4 or NGC 7023 or Iris Nebula, a reflection nebula in the constellation Cepheus Circumferential Road 4 or C-4, an arterial road of Manila, Philippines Ken-Ō Expressway (includes some sections of Shin-Shōnan Bypass), route C4 in Japan Omotesandō Station, a Tokyo Metro subway station (station numbers C-04, G-02, H-02) People C4 (rapper), a rap music producer from Birmingham, England Clarence Mitchell IV, American radio host and former politician Chris Turner, sometimes credited as Chris Heiner, a.k.a. "C4", Australian musician, part of Modern Day Poets (MDP) alongside Tim Turner (a.k.a. "DubLT") and Joel Turner Computing C4 (conference), a Macintosh software developers conference C4 Engine, a next-generation 3D game engine C4 model (software), a graphical notation technique for diagramming software architecture Cx4 chip, an add-on microprocessor chip employed by certain Super NES game cartridges (often incorrectly referred to as the C4 chip) Controlled collapse chip connection or flip chip, a method for interconnecting semiconductor devices VIA C4, a planned design of central processing unit for a personal computer Arts, entertainment, and media Music C4 (American band), a neo-classical metal band set up by Michael Angelo Batio C4 (French band), French boyband C4 (mixtape), mixtape by American rapper Kendrick Lamar C4, scientific pitch notation for the note "Middle C" (261.626 Hz) C4 Records, a record label Tha Carter IV, album by American rapper Lil Wayne Other uses in arts, entertainment and media C4 (New Zealand TV channel), a former New Zealand television music channel 1. c4, also called the English Opening, a chess opening Channel 4, a UK television channel broadcasting since 1982 Mathematics, science, and technology Biology C4: an EEG electrode site according to the 10-20 system Apolipoprotein C4, a protein encoded by the APOC4 gene c4 antisense RNA, a non-coding RNA ATC code C04 Peripheral vasodilators, a subgroup of the Anatomical Therapeutic Chemical Classification System C4 carbon fixation, a pathway for carbon fixation in photosynthesis that produces C4 plants Cervical spinal nerve 4, a nerve originating in the neck Cervical vertebra 4, one of the cervical vertebrae of the vertebral column C04, oral cancer ICD-10 code Complement component 4, a protein involved in the intricate complement system C4 fragments, one of the types of products of catabolism pathways Math , the cyclic group of order 4 C4, the fourth pure "core" module in the Edexcel A-level mathematics examination Other uses