The SpaceX mafia
PayPal's early employees went on to build much of the consumer internet. Two decades later, SpaceX alumni are doing the same for hard technology: rockets, reactors, missiles, factories and the software that runs them. Here is who they are and what they've built.
Why SpaceX produces founders
SpaceX gives engineers a lot of responsibility early, runs hardware on short test cycles, and expects the people who design a part to also make it work in flight. People who leave carry that approach with them. Many start companies in areas the aerospace industry used to move slowly in, such as propulsion, satellite manufacturing and defense production. Others take the same habits into unrelated fields like home batteries, grocery software and building materials.
By the numbers
- 100 companies with at least one SpaceX alum as founder
- $13.9B in disclosed funding, a lower bound
- 12 valued at $1 billion or more
- 13 US states with headquarters, plus Canada and South Korea
- 109 alumni founders with profiles, 6 of whom have founded more than one company
The largest companies
- Base Power: Home battery systems that double as a distributed power plant. $2.2B disclosed.
- Castelion: Low-cost hypersonic weapons built at production scale. $1.45B disclosed.
- Relativity Space: Reusable medium-lift rockets built with automated manufacturing. $1.3B disclosed.
- Impulse Space: Orbital transfer vehicles for last-mile delivery in space. $1.02B disclosed.
- K2 Space: Very large, high-power satellites designed for heavy-lift rockets. $950M disclosed.
- Rebellions: Energy-efficient AI inference chips. $850M disclosed.
- Hermeus: Hypersonic aircraft, starting with uncrewed high-speed jets. $510M disclosed.
- Radiant: Portable nuclear microreactors that ship in a container. $505M disclosed.
- Apex: Standardized satellite buses built like products, not projects. $500M disclosed.
- Long Wall: Missile defense interceptors and hypersonic test vehicles. $500M disclosed.
- Starcloud: Data centers in orbit, powered by continuous sunlight. $454M disclosed.
- Muon Space: Satellite constellations for Earth and climate data, built at scale. $386M disclosed.
See the full impact data or browse all 100 companies.
Serial founders
- Brogan BamBrogan founded Arrivo and Ethos Space and Hyperloop One.
- Jim Cantrell founded Phantom Space and Vector Launch.
- Jordan Noone founded Relativity Space and Zoo.
- Josh Giegel founded Gambit and Hyperloop One.
- Mike Smayda founded Fortastra and Hermeus.
- Porter Harris founded Power.Global and Romeo Power.
Frequently asked questions
What is the "SpaceX mafia"?
It's an informal name for the growing group of former SpaceX employees who have gone on to found companies, borrowed from the "PayPal mafia" of the 2000s. This index tracks 100 of those companies.
How much money have companies founded by SpaceX alumni raised?
The companies in this index have disclosed at least $13.9B in funding. That figure only counts publicly reported rounds, so the true total is higher.
Which SpaceX alumni companies are the largest?
By disclosed funding, the largest include Base Power, Castelion, Relativity Space, Impulse Space, K2 Space. 12 companies have been valued at $1 billion or more.
What industries do former SpaceX employees start companies in?
Space is the biggest category, but alumni have also founded companies in energy (including nuclear), defense, manufacturing, software and AI, mobility, climate, health and robotics.
Where are these companies based?
Most are in the United States, across 13 states. California, where SpaceX grew up, has by far the largest cluster, followed by Washington and Texas.
Is this site affiliated with SpaceX?
No. It is an independent directory and is not affiliated with or endorsed by SpaceX.