Sebastian Fischer is Co-Founder and CEO at Wardstone, a Y Combinator backed space defense company building satellites equipped with interceptors to defend against hypersonic and ballistic missiles. Wardstone is pursuing the emerging $40B per year space defense market as part of America's Golden Dome initiative.

Sebastian studied Aerospace Engineering at MIT and completed a dual MS/MBA at Harvard. He has over 10 years of engineering and product experience, having held leadership roles at Amazon Prime Air, Cruise Self-Driving, Lockheed Martin, and NASA on planetary spacecraft.

Sebastian and his brother Tobias built and demoed a live ground-based missile intercept during YC, and Wardstone took 2nd place at YC's Product Showcase. The company has built relationships with multiple military agencies including Air Force Research Labs, AFWERX, and Space Systems Command.

Wardstone has raised approximately $5 million in seed funding and is preparing to test its first prototype interceptor vehicle on a suborbital flight in spring 2026. The company is pursuing an Air Force $3M Space Based Interceptor SBIR grant.

Wardstone aims to outcompete traditional defense primes by delivering in-space interceptor solutions that are orders of magnitude more cost-effective on a cost-per-kill basis. The company's goal is to provide defensive capabilities for the United States and its allies against emerging space threats.