That's difficult to answer without knowing how small is small, what sort of soil you have, how much sun you get etc. Are you after evergreen shrubs? One difficulty is that most don't stay small...if the space you have available is tiny, a shrub could overwhelm it.

Anyway, look at Pittosporum tenuifolium 'Tom Thumb' to start you off. Dark leaves, a compact rounded shape, and evergreen.

There is a pic of the above small shrub,as recommended by Spritz,..the last one on page 2 of my pics..just starting into new growth,before they turn to the darker colour.Very hardy and compact..if this is the kind of shrub you are looking for.... if not,please give a bit more info,as to size etc,that you would like.

Whether its sunny (southfacing) or very shady is a crucial piece of information for providing suggestions, as well as the size of the area, and where you live in UK - some plants are hardy down south and west, but not up North. That's why you're asked what area you live in...