Dual-Phase, High-Entropy Boride–carbide Ceramics Were Densified by Pressureless Sintering. Relative Densities Up to Approximately 96% Were Obtained for Ceramics Containing About 30 Vol% High-Entropy Boride and 70 Vol% High-Entropy Carbide. Isostatic Pressing at 200 MPa Resulted in Higher Relative Densities of Both the Green Bodies and Final Ceramics Compared to Uniaxial Pressing. the Highest Relative Density of 96.3% Was Achieved for a Ceramic that Was Isostatically Pressed at 200 MPa and Sintered at 2300°C for 2 H. Grain Sizes of the Resulting Ceramics Were Approximately 2 µm. This is the First Report of Pressureless Sintering of Dual-Phase, High-Entropy Boride–carbide Ceramics.