People Operations Specialist
About the role
Why Castelion, Why Now Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus and technical excellence are decisive advantages - and we are building a team that can deliver real capability, not just concepts. This is a rare opportunity to join at an early stage, where your work will directly shape critical systems, influence major technical decisions, and have immediate, real-world impact. Castelion is looking for a People Operations Specialist to support and scale the systems and processes that power our team. This role sits at the intersection of HR and Recruiting, helping ensure we hire effectively, onboard seamlessly, and maintain strong operational rigor as we grow. You'll play a key role in executing and improving day-to-day people operations - supporting recruiting workflows, maintaining clean and reliable data, and helping bring structure and visibility to hiring and employee processes.
Responsibilities
- Support core HR processes including onboarding, offboarding, and employee lifecycle activities
- Maintain and ensure accuracy of employee data within HR systems (HRIS)
- Assist with compliance-related processes, documentation, and audits
- Support employee communications, documentation, and internal process improvements
- Support recruiting workflows from sourcing through offer stage
- Maintain ATS data integrity and ensure consistent process usage across teams
- Coordinate interview scheduling and support candidate experience as needed
- Help track pipeline activity and ensure visibility into hiring progress
- Build and maintain basic dashboards and reports on recruiting and headcount metrics
- Track key data points such as pipeline health, time-to-fill, and offer acceptance rates
- Support creation of materials that communicate hiring progress and insights to leadership
Requirements
- 2+ years of experience in People Operations, HR, Recruiting Operations, or similar role
- Experience working with ATS and/or HRIS systems (e.g., Ashby, Greenhouse, Rippling, etc.)
- Strong organizational skills and attention to detail
- Proficiency in Excel or Google Sheets
- Ability to obtain and maintain a U.S. government–issued security clearance (U.S. citizenship required)
Preferred Skills and Experience
- Experience in a startup or high-growth environment
- Familiarity with recruiting metrics and HR processes
- Experience supporting technical recruiting teams
- Exposure to compliance and multi-state employment practices
Benefits and Perks
- Meaningful long-term equity for all full-time employees
- Four (4) weeks of paid time off
- Ten (10) company-paid holidays
- Comprehensive health benefits – 100% employee-covered medical and strong dependent coverage, plus dental and vision plans
- Paid parental leave
- $100 monthly fitness stipend
- Onsite EV charging
- Catered meals and company-covered food during high-demand periods
- Fully stocked kitchen