Job description

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. People Operations Specialist 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 Basic Qualifications • 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 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 Other Duties Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job. Duties, responsibilities and activities may change at any time with or without notice. Benefits And Perks All full-time employees are granted meaningful long-term equity, sharing in the company's significant growth trajectory. We offer four (4) weeks of paid time off, ten (10) company-paid holidays, and comprehensive health benefits - including 100% employee-covered medical and strong dependent coverage, along with dental and vision plans. We also provide paid parental leave to support growing families, a $100 monthly fitness stipend to promote health and performance, and onsite EV charging for convenience. In addition, employees enjoy perks like catered meals, company-covered food during high-demand periods, and a fully stocked kitchen to stay fueled throughout the day. While this position does not currently require a U.S government-issued security clearance, it may in the near future. Therefore, the ability to obtain and maintain a U.S. government–issued security clearance is required. U.S. citizenship is required, as only U.S. citizens are eligible for a security clearance. Affirmative Action/EEO Statement 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.

Requirements

Must-haves

Why Castelion, Why Now
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.
People Operations Specialist
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
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
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
Other Duties

Nice-to-haves

Preferred Skills and Experience

Application prep

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Platform: manatal
Effort: medium

Benefits

Benefits detected in the listing.

Dental

Vision

Paid Time Off

Parental Leave