2B

2B or 2-B may refer to:
 * 2B (band), a Portuguese band
 * 2B (film), a 2009 science fiction film
 * 2B lead, a grading of pencil hardness
 * 2B (Nier: Automata), the video game's main protagonist
 * 2b Theatre Company, a theatre company in Halifax, Nova Scotia
 * 2b2t, а Minecraft server with no rules
 * Aerocondor, IATA airline code 2B
 * Alpha-2B adrenergic receptor, a type of protein structure
 * Haute-Corse, French department 2B (northern Corsica)
 * IARC group 2B
 * Second baseman, a fielding position in baseball
 * Double (baseball), a type of base hit
 * Stalag II-B, a prisoner of war camp in Germany
 * Transcription factor II B, a type of protein structure
 * Type IIb diamond, a classification of natural diamonds
 * Type IIB string theory, a physical theory about the basic substance of the universe
 * II-b or IIb, a subtype of Type II supernova