The equiatomic, high-entropy alloy FeMnNiCoCr crystallizes as a face-centered cubic solid solution and is one of the few examples of high-entropy alloys which can be tailored by means of classical metallurgical processes. Thus, FeMnNiCoCr has attracted most interest by the scientific community among the class of high entropy alloys so far. We present a comprehensive analysis of the low temperature deformation behavior of FeMnNiCoCr on the basis of quasistatic tensile and compressive tests at temperatures ranging from 4.2 K to room temperature. The appearance of different kinds of deformation phenomena in this temperature range as well as their interactions are discussed: (i) serrations at very low temperature (4.2 K), (ii) deformation twinning (4.2 K and 77 K), as well as (iii) dislocation slip in a solution hardened material. The importance of deformation twinning for stable work hardening rate over an extended stress as well as strain range is addressed on the basis of orientation imaging microscopy studies. The work hardening of FeMnNiCoCr at low temperature is compared to well-understood materials like single-phase copper alloys or TWIP steels exhibiting different ratios of dislocation slip and deformation by twinning depending on their stacking fault energy.