Verbascum thapsus (great mullein or common mullein) is a species of mullein native to Europe, northern Africa, and Asia, and introduced in the Americas and Australia.

It is a hairy biennial plant that can grow to 2 meters tall or more. Its small yellow flowers are densely grouped on a tall stem, which grows from a large rosette of leaves. It grows in a wide variety of habitats, but prefers well-lit disturbed soils, where it can appear soon after the ground receives light, from long-lived seeds that persist in the soil seed bank. It is a common weedy plant that spreads by prolifically producing seeds, but it rarely becomes aggressively invasive, since its seeds require open ground to germinate. It is a very minor problem for most agricultural crops, since it is not a very competitive species, being intolerant of shade from other plants and unable to survive tilling. It also hosts many insects, some of which can be harmful to other plants. Although individuals are easy to remove by hand, populations are difficult to eliminate permanently.