Relex may refer to:

• R'lyeh, a fictional city described by H. P. Lovecraft
• Relexification, a linguistic process
• Relex, the former computer software company that provided software and services for analyzing design and field data to assist in evaluating and improving product reliability and safety (acquired by PTC, and functionality integrated into Windchill)
• DG RELEX, the Directorate-General for External Relations (European Commission)
• ReLEx SMILE(small incision lenticule extraction), a flap procedure in Refractive surgery
• RELEX Solutions software company that provides solutions and services for retailers and wholesalers for demand forecasting, automated replenishment, space planning, and assortment optimization.

• Nilson de Souza Zille
• Nilson Matta
• Nilson Nelson Gymnasium
• Nils Otto Gustaf Nordenskioeld
• Nils Otto Gustaf Nordenskiold
• Nils Otto Gustaf Nordenskjoeld
• Nils Otto Gustaf Nordenskjold
• Nils Otto Tank
• Nils Ove Hellvik
• Nils Peder Langvand
• Nils Pedersen Igland
• Nils Peter Heitman
• Nils Peter Laberg Heitman
• Nils Petersen
• Nils Petter Gleditsch
• Nils Philip Gyldenstolpe
• Nils Pichinot
• Nils Plain
• Nils P. L. Heitman
• Nils Quensel
• Nils Ragvaldsson (Vaelingeaetten)
• Nils Ragvaldsson (Valingeatten)
• Nils-Reinhardt Christensen
• Nils Reinhardt Christensen
• Nils Retterstøl