About Castelion

Castelion is bringing a new approach to defense development and production: one that focuses on short, iterative design cycles, rapid testing in development, and modern commercial manufacturing strategies for production at scale. We’re designing, building, and testing next generation long range strike weapons systems to give America and its Allies a definitive edge and deter future conflicts.

Executive Assistant

As Executive Assistant to the C-Suite, you will serve as a trusted partner in keeping our leaders organized, prepared, and focused. You will work closely with leadership across the company, helping ensure priorities are advanced efficiently and communication flows seamlessly. This role is 100% onsite in our Torrance headquarters, embedded in the action alongside engineering and operations teams.

Responsibilities

• Manage and optimize the CEO’s calendar, including scheduling internal/external meetings, coordinating travel, and managing logistics.
• Act as a gatekeeper and liaison, ensuring clear and timely communication across teams, customers, and investors.
• Track action items, deadlines, and follow-ups for the CEO and other Leaders—owning the details and ensuring nothing falls through the cracks.
• Support preparation for key meetings, including compiling agendas, briefings, presentations, and notes.
• Help facilitate execution of high-priority projects across the company.
• Organize team offsites, board meetings, and special events.
• Handle confidential information with discretion, professionalism, and integrity.

Qualifications

• 3+ years of experience supporting a senior executive, ideally in a fast-paced startup or high-stakes environment.
• Proven ability to manage complex calendars and prioritize scheduling across multiple stakeholders and time zones with accuracy and discretion.
• Experienced in coordinating travel logistics, including flights, hotels, ground transportation, and agendas—anticipating changes and solving problems on the fly.
• Proficient in managing expense reports and reconciling financial documentation with accuracy and timeliness.
• Capable of producing polished support materials such as slide decks, memos, briefing documents, and follow-up notes.
• Adept with tools and technologies that streamline EA responsibilities—e.g., Outlook, Teams, Google Workspace (Calendar, Docs, Sheets), Microsoft Office, Slack, Zoom, Expensify, TripActions, Notion, and scheduling tools like Calendly or Motion.
• Exceptional organizational skills, attention to detail, and follow-through—you don’t drop balls.
• Unflappable under pressure, with the ability to juggle competing priorities and tight deadlines with a calm, solutions-first mindset.
• Thrives in ambiguity and operates with speed, discretion, and sound judgment.
• Mission-driven, with a strong work ethic and a “no task too small” attitude.
• 100% onsite in Torrance—you value being physically present to anticipate and adapt to your executive’s needs in real time.

All employees are granted long-term stock incentives as part of their employment as Castelion. All employees receive access to comprehensive medial, vision, and dental insurance, and the company offers three weeks of paid time off per year.

Leadership Qualities

Bias to Action and Creative Problem Solving. Desire and experience questioning assumptions in ways that lead to break through ideas that are ultimately implemented. Successfully bring in applicable processes/concepts/materials from other industries to achieve efficiency gains. Ability to personally resolve minor issues in development without requiring significant support.

High Commitment, High Initiative. A successful candidate will have a genuine passion for Castelion’s mission and consistently look for ways to contribute to the company’s technical goals and prevent hardware blockers. Ability to work in a fast paced, autonomously driven, and demanding atmosphere. Strong sense of accountability and integrity.

Clear Communicator. Proactively communicates blockers. Trusted in previous roles to be voice of company with regulators, suppliers, gate keepers and customers. Capable of tactfully managing relationships with stakeholders to achieve company-desired outcomes without compromising relationships. Emails, IMs and verbal interactions are logical, drive clarity, and detailed enough to eliminate ambiguity.

ITAR Requirements:

• To conform to U.S. Government export regulations, applicant must be a (i) U.S. citizen or national, (ii) U.S. lawful, permanent resident (aka green card holder), (iii) Refugee under 8 U.S.C. § 1157, or (iv) Asylee under 8 U.S.C. § 1158, or be eligible to obtain the required authorizations from the U.S. Department of State.

Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.