This paper introduces a novel strategy to design high-entropy alloys (HEAs) using the eutectic alloy concept, aiming to achieve a microstructure composed of alternating soft fcc and hard bcc phases. The authors designed an Al0.0CrFeNi2.1 eutectic high-entropy alloy (EHEA), which exhibited a fine lamellar fcc/B2 microstructure. This EHEA demonstrated unprecedented combinations of high tensile ductility and high fracture strength at room temperature, with mechanical properties maintained up to 700°C. The excellent properties are attributed to the balanced structure and the advantages of eutectic alloys, such as good castability and resistance to compositional segregation. The study highlights the potential of this new class of alloys for large-scale industrial production and their superior performance compared to conventional high-temperature alloys like NiAl and NiAl/Cr(Mo) eutectic alloys. The research was supported by various grants from the National Science Foundation of China and the Chinese Ministry of Education.This paper introduces a novel strategy to design high-entropy alloys (HEAs) using the eutectic alloy concept, aiming to achieve a microstructure composed of alternating soft fcc and hard bcc phases. The authors designed an Al0.0CrFeNi2.1 eutectic high-entropy alloy (EHEA), which exhibited a fine lamellar fcc/B2 microstructure. This EHEA demonstrated unprecedented combinations of high tensile ductility and high fracture strength at room temperature, with mechanical properties maintained up to 700°C. The excellent properties are attributed to the balanced structure and the advantages of eutectic alloys, such as good castability and resistance to compositional segregation. The study highlights the potential of this new class of alloys for large-scale industrial production and their superior performance compared to conventional high-temperature alloys like NiAl and NiAl/Cr(Mo) eutectic alloys. The research was supported by various grants from the National Science Foundation of China and the Chinese Ministry of Education.