Beta is the second letter of the greek alphabet (β). Beta may also refer to:

In mathematics and statistics:

• Beta function in mathematics
• Beta distribution in statistics
• Beta coefficient in finance

In physics:

• Beta-function in quantum field theory
• Beta particle in subatomic physics (see also Beta decay
• Beta (velocity) in special relativity
• Thermodynamic beta in thermodynamics/statistical mechanics
• Common-emitter current gain of a transistor in electronics
• the ratio of thermal to magnetic energy density in a plasma (see Plasma_parameters#Dimensionless)