A fuel injector (20) comprising a fuel injector body (24) having a central longitudinal axis (L), a plate element (46) for coupling the fuel injector (20) to a fuel injector cup (44), a snap ring (52) and a spring element (60) is specified. The snap ring (52) is operable to block a movement of the fuel injector body (24) relative to the plate element (46) in a first direction (D1) of the central longitudinal axis (L). The spring element (60) is operable to bias the plate element (46) in a second direction (D2) of the central longitudinal axis (L) opposing the first direction (D1) of the central longitudinal axis (L) to prevent a movement of the plate element (46) relative to the fuel injector body (24) during coupling to the fuel injector cup (44). Further, a fuel injector assembly (40) with a fuel injector (20) and a coupling device is specified.
