Human Resources Manager

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. Were designing, building, and testing next generation long range strike weapons systems to give America and its Allies a definitive edge and deter future conflicts.

Human Resources Manager

We are looking for a resourceful, hands-on Human Resources Manager to serve as the foundational people leader at Castelion. This is a high-impact role for someone excited to wear multiple hats -supporting hiring, onboarding, compliance, employee relations, culture building, and HR infrastructure. You'll work closely with leadership to ensure our people practices keep pace with our growth and reflect our values of excellence, urgency, and trust. This role is 100% onsite at our Torrance, CA headquarters - embedded in the action alongside engineering and executive teams.

Responsibilities

• Serve as Castelion's primary HR lead: owning and evolving HR operations across our Torrance HQ and satellite sites
• Manage onboarding, offboarding, benefits administration, and employee lifecycle processes
• Provide employee relations support and guidance to leadership and employees
• Ensure compliance with federal, state, and local labor laws, including CA-specific requirements
• Help define and reinforce our company culture as we scale
• Build scalable HR systems, policies, and programs from scratch
• Lead initiatives related to performance reviews, compensation benchmarking, and employee engagement
• Support internal communications, employee check-ins, and workplace experience

Basic Qualifications

• 5+ years of HR experience, ideally including time at a fast-paced startup or small company
• Confident navigating ambiguity and building from zero: startup DNA is a must
• Strong working knowledge of HR compliance and California labor law
• Highly trustworthy, empathetic, and people-focused
• Detail-oriented, organized, and responsive: you get stuff done
• Comfortable working in an in-person environment and across different sites

Preferred Skills and Experience

• Experience supporting engineering-heavy or government-adjacent teams

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. The 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.

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