OP50 may refer to:

• Op. 50 (disambiguation), several opuses
• a strain of Escherichia coli used for maintenance of Caenorhabditis elegans cultures

• List of Space Island One episodes
• List of space launch system designs
• List of space launch systems
• List of space observatories
• List of space probes
• List of space probes powered by non-rechargeable batteries
• List of space programmes
• List of Space Sheriff Shaider episodes
• List of space shuttle landing runways
• List of Space Shuttle military missions
• List of space shuttle missions
• List of Space Shuttle orbiters
• List of space stations
• List of spacewalks and moonwalks
• List of spacewalks since 2000
• List of spacewalks since 2015
• List of spacewomen
• List of Spain Davis Cup team representatives
• List of Spain international footballers born outside Spain
• List of Spain national football captains
• List of Spaniards by net worth
• List of Spanish artists nominated for MTV Europe Music Awards
• List of Spanish autonomous communities by gross domestic product
• List of Spanish autonomous communities by GRP
• List of Spanish cars