Virginia Creeper
Is this poison ivy?
While Virginia Creeper is often planted intentionally as an ornamental vine, it can often crop up in places where you didn't invite it and get out of control. It's also often confused with poison ivy.
The easiest way to tell the difference between Virginia creeper and poison ivy is to count the leaflets: Virginia creeper has 5 leaflets (it's scientific name is Parthenocisis quinquefolia, for 5 leaves), while poison ivy has 3 leaflets.
Virginia creeper is an agressive vine that can grow 50-feet tall. Planted in the right place, it can be a beautiful ornamental with vivid fall foliage color.