Catberry Holly (Ilex mucronata).
Perhaps you are most familiar with the evergreen hollies, such as our native American Holly (Ilex opaca) or the ornamental non-native hollies such as Japanese Holly (I. crenata) or Nellie Stevens Holly (Ilex x 'Nellie R. Stevens'). But many of our native hollies are deciduous as well as lovely.
The Catberry Holly (Ilex mucronata) loses its leaves in the fall but often retains its bright red berries into winter. It is a shrub of wet places. Which is where I found this specimen near a bog on a high mountain plateau at the southern most reach of its range.
Location: Dolly Sods Wildernes, West Virginia.