Lowest Mono-Phasic:
Alesse - 20mcg E, .1mg levonorgestrel
Aviane (generic) - 20mcg E, .1mg levonorgestrel
Levlite - 20mcg E, .1mg levonorgestrel
Loestrin 1/20 - 20mcg E, 1mg norethindrone acetate
Loestrin Fe 1/20 - 20mcg E, 1mg norethindrone acetate
Microgestin Fe 1/20 - 20mcg E, 1mg norethindrone acetate
Lowest Multi-Phasic:
Mircette - 20mcg E (21 days), 0 E (2 days), 10mcg E (5 days), desogestrel .15mg (21 days)
Cyclessa - 25mcg E (21 days), desogestrel .10mg (7 days), desogestrel .125mg (7 days)
There are other multiphasic pills that have some pills at 25mcg, but they also contain pills that go up to 35mcg so I didn't include those. I don't consider 35mcg low - even if you only take that much a couple days a month!