WASHINGTON — Castilian, a defense technology startup led by former SpaceX engineers, announced Dec. 5 that it has raised $350 million in Series B financing to accelerate high-volume production of hypersonic weapons for the Pentagon.
The California-based company has positioned itself as a vertically integrated manufacturer of hypersonic missiles, an area where US officials admit lagging behind China and Russia. Castilian’s first weapons are being developed for the US Army and Navy, and the firm has secured several research and development contracts from the Air Force Research Laboratory.
The latest financing was led by Altimeter Capital and Lightspeed Venture Partners, with participation from Lavrock Ventures, Andreessen Horowitz, General Catalyst, First In, Space VC, Cantos, Blueyard, Avenir, Champion Hill and Interlagos. The support reflects investors’ growing appetite for hardware-focused defense startups that promise faster design cycles and commercial-style production methods.
CEO and co-founder Brian Hargis said Castilian wants to “close the U.S. hypersonic capability gap against China and Russia.” “This funding lets us build faster, test repeatedly, and produce in quantities that matter in the real world.”
The company last month unveiled plans for a 1,000-acre campus in New Mexico dedicated to next-generation hypersonic systems. The site is expected to support solid rocket motor production, static testing and final assembly of completed rounds.
Investors say the company’s fast pace has been central to its appeal. Eric Chrisman, partner at Altimeter Capital, said Castilian was founded by “a special team of SpaceX alumni who, in just 2.5 years, took a clean-sheet hypersonics from concept to 25+ flight tests and major integration contracts.”
Alex Paulin, partner at Leverock Ventures, said that “Hypersonics only make sense if you can build them at scale. The team at Castilian understands this… We are proud to be an early supporter of a team focused on delivering capability, not just concepts.”
The Series B raise follows a steady funding raise. In January 2025, Castilian reported a $100 million investment that included $70 million in Series A capital led by Lightspeed and a $30 million venture loan from Silicon Valley Bank. This came after a seed round of $14.2 million.
