R66

R66 may refer to:
 * R66 (South Africa), a road
 * HD 268835, a star
 * HMS Zambesi (R66), a destroyer of the Royal Navy
 * R66: Repeated exposure may cause skin dryness or cracking, a risk phrase
 * R66 Protocol, a file transfer protocol
 * Robinson R66, a helicopter
 * Small nucleolar RNA R66