1B

1B may refer to:

Science and technology

 * Alpha-1B adrenergic receptor
 * Arginine vasopressin receptor 1B
 * Interferon beta-1b
 * Melatonin receptor 1B
 * The ASCII hexadecimal code for the escape character
 * 1b as one billion

Sport

 * First baseman
 * Single (baseball)

Transport

 * Axle arrangement on steam locomotives corresponding to a 2-4-0 wheel arrangement
 * GCR Class 1B, a class of British 2-6-4T steam locomotive
 * National Highway 1B (India, old numbering)