where are you located? if in zone 7 or warmer, southern bayberry (wax myrtle) might work for you. if colder than zone 7, go with the northern bayberry. these are tough plants that do not require much other than pruning for shape, if desired, after establishment. be sure to get both male and female plants to have the attractive berries that birds are so fond of. the foliage is aromatic, as well. in my area of east central alabama, they are semi-deciduous but still retain enough foliage through winter to qualify as a screen. see link below for more information of both types.

southern bayberry

I second the wax myrtle, they have a great growth rate and are dense. They're also popular with native wildlife for nesting and food (berries are adored by Yellow-rumped warblers which are found in some regions during the winter) and an odd caterpillar, the larva of the Red-banded hairstreak butterfly eat the dead leaves under the plant. Do NOT plant this plant near areas that receive a lot of nitrogen fertilization, especially if you live in Florida, because that has led to some developing a fatal root rot in that state.

There's also hollies (more slow-growing though) and Magnolia which are also dense (though, the magnolia might require a hedge in front of them for proper privacy screening).

Eastern red cedar (do not plant if anyone has allergies to pollen!) and white pine might also be suitable depending on region.

I also feel the need to plug in one of my absolute fave shade trees, the native Red Mulberry. A wonderful early season fruit that produces even when not fertilized (so female plants are suitable to buy even for people with allergies, they produce no pollen yet bear fruit). Unfortunately, the fruit stains pathways and driveways which partially explains why it's not super common. They make good shade trees and are decently fast growing. they aren't as dense as the others, however, so if there's no fence or hedge they might not provide adequate privacy.

Go with the thuja(also know as the green giant)..I planted 6 small ones 7 years ago and they are so pretty and tall already,They love full sun.Hers a picture of them back in the winter