Castelion, founded in 2022 by former SpaceX engineers including Bryon Hargis, Sean Pitt, and Andrew Kreitz, is a defense technology company building affordable, mass-producible hypersonic strike weapons. The company applies rapid, vertically integrated, software-driven engineering, modeled on SpaceX's iterate-and-test approach, to drive down the cost and timeline of long-range precision munitions like its Blackbeard system. Castelion designs, builds, and tests in-house, using simulation, autonomy, and AI-assisted manufacturing to compress development cycles that traditionally span decades. As the US prioritizes hypersonic capability and scalable defense production, Castelion has attracted significant capital: a $100M Series A in early 2025 (including $70M led by Lightspeed) followed by a $350M Series B in December 2025 led by Altimeter Capital and Lightspeed, with Andreessen Horowitz, General Catalyst, and others, bringing total funding to roughly $450M.