SELEX may refer to one of the following:
- SELEX Galileo, part of Finmeccanica's defence electronics sector
- SELEX Sistemi Integrati, a civil and military radar company which is part of Finmeccanica
- SELEX Communications, a military and civil communications systems supplier which is part of Finmeccanica
- Systematic Evolution of Ligands by Exponential Enrichment, a molecular biology technique used in drug development
- SEgmented Large-X baryon spectrometer EXperiment, run at Fermilab to study charmed baryons.