Grass seeds for very shady lawns
There is no such thing as a shade loving turf. Fine fescues [hard, sheep and (creeping) red fescue] are the most tolerant of the cool season turfgrasses. They have a much different texture that tall fescue or Kentucky bluegrass so some people don't like the appeaerance. The fine fescues don't tolerate a lot of heavy use, but they do require less fertilizer than other cool season grasses.
If you're getting less than 6 hours of sun a day in these spots, consider alternative ground covers. While typically they require much less maintenance than turf, they are not very tolerant of traffic.