Direct Current (DC) fast charging enables supply of megawatt (MW) scale DC power to the large battery systems of Heavy-Duty Electric Vehicles (HDEVs), such as electric trucks, buses, ferry and construction machinery. This contrasts with Alternating Current (AC) charging, which is limited by the capacity of the On-Board Charger (OBC) that converts AC to DC to charge the battery. In DC fast charging, however, the Electric Vehicle Supply Equipment (EVSE) delivers DC power directly to the HDEVs, bypassing the OBC. The feasibility of fast DC charging has been driven by advancements in semiconductor technology offering higher voltage and current handling capabilities as well as improvements in battery energy density. Ongoing research indicates continued growth in both semiconductor power handling and battery storage capacity, further strengthening the case for fast DC charging. Key benefits include significantly higher charging efficiency, drastically reduced charging times, and lower driver fatigue. However, unlike AC systems, DC based charging infrastructure presents unique protection challenges. These challenges arise from the absence of natural current zero-crossings of DC current and the limited commercial availability of pure DC breakers. This paper presents a concise review of existing protection technologies applicable to DC fast-charging infrastructure, identifying critical gaps in current approaches and evaluating potential solutions for Low Voltage (LV, <1.5 kV) and Medium Voltage (MV, 1.5–35 kV) DC applications. Then a downsized 10 kW prototype of an Ultra-Fast Active Resonance Current Source-Based Hybrid DC Circuit Breaker (UFRDCB) has been developed and experimentally validated as a proof of concept. The prototype successfully interrupts a 1 kA continuous DC current in less than 500 μs, and the corresponding test results are presented and discussed. Finally, the paper outlines a forward-looking roadmap for advancing protection technologies that are critical to the safe and reliable operation of megawatt-scale DC fast-charging infrastructure for HDEVs in the United States and globally.