Mandrake

 refers to many things around the Doctor Who universe and the real world.

In-universe
In 800, French king and Holy Roman Emperor Charlemagne lost a food taster to mandrake poisoning. (PROSE: The Lonely Computer)

Mandrake was a drug that was exploited by the Mandragora Helix in the 1990s in an attempt to conquer Earth. (COMIC: The Mark of Mandragora)

Mandrake was the new name for the reorganised Rechauffe corporation, secretly a front for the Crimson Chapter of the Orbus Postramo, attempting to craft a virus that could wipe out humanity. (AUDIO: Fatal Consequences)

In the 24th century, brain experiments by Crozier moved a mind parasite named Mandrake the Lizard King into Peri Brown's brain for a while. (AUDIO: The Widow's Assassin)

In the 41st century, Erimem tricked Sekhmet into drinking her blood which was poisoned with distilled mandrake root that was contained in Erimem's signet ring. (AUDIO: The Bride of Peladon)

Behind the scenes

 * The mandrake plant (genus Mandragora) belongs to the nightshade family, along with tomatoes and potatoes. It is a hallucinogen and can be toxic in large doses.