suggestions for a evergreen shrub for the back of a bed

Hello all,

I am in zone 7a and have a large, almost empty bed. On one end I have our shed, which has an acuba next to it, and 30 ft to the left I have a dogwood. I have some idea of the shrubs and perennials that will go inbetween these two, but would like an evergreen as the backdrop for these deciduous, flowering plants, so the bed is more enjoyable year round.

This bed gets almost full sun, except for the space where the acuba is located. And for reference some of the shrubs/perennials I am thinking of are spireas, hydrangeas (mop head style), knock-out roses, amsonias, and some smaller grasses. By the shed, in the remaining shade area there are some hostas.

This bed is on a fence line, which is a 6ft board on board fence.
Please give me some suggestions! I ideally would like something 6ft-15ft, evergreen, that doesn't have a huge spread. I think that a non-flowering evergreen would be a nice contrast to all the shrubs I have planned for here.

Also if you think I am doing too much, or that I should just go for it without an evergreen back hedge please let me know that too!
Thanks,
Lisa