This reflects my age. Quite a few of the airlines no longer exist
Domestic:
AirCal
Alaska
Allegheny
American
America West
Braniff
Continental
Delta
Eastern
Frontier
Lake Central
Northwest
Piedmont (the old one)
PSA (likewise, the old one)
Southwest
TWA
United
USAir
Virgin America
World (they used to run a flight between LA and SFO in the 70s...$25 round trip!)
International:
Air France
Austrian
bmi British Midland (long gone, but my favorite by far)
British
Czech
KLM
LOT Polish
Malev Hungarian
Martinair (pretty awful, but cheap)
New Zealand
PanAm (my first international flight 50 years ago)
Qantas
Tyrolean (there's a reason it no longer exists...incredibly rude personnel, bad food, old planes and expensive)