The term SEAC can stand for:
- Senior Enlisted Advisor to the Chairman of the United States Joint Chiefs of Staff, the senior non-commissioned member of the United States armed forces
- SESAR European Airports Consortium, the operators of six major European airports joined forces for participation in SESAR
- South East Asia Command, a World War II Allied military command
- Standards Eastern Automatic Computer, a first-generation electronic computer built in 1950
- Student Environmental Action Coalition, a coalition of environmental groups in the United States and Canada
SEAC (Standards Eastern Automatic Computer or Standards Electronic Automatic Computer) was a first-generation electronic computer, built in 1950 by the U.S. National Bureau of Standards (NBS) and was initially called the National Bureau of Standards Interim Computer, because it was a small-scale computer designed to be built quickly and put into operation while the NBS waited for more powerful computers to be completed (the DYSEAC). The team that developed SEAC was organized by Samuel N. Alexander. SEAC was demonstrated in April 1950 and in May 1950 it went into full production, making it the first fully functional stored-program electronic computer in the US.