The titan arum or Amorphophallus titanum (from Ancient Greek amorphos, "without form, misshapen" + phallos, "penis", and titan, "giant") is a flowering plant with the largest unbranched inflorescence in the world. The largest single flower is borne by the Rafflesia arnoldii; the largest branched inflorescence in the plant kingdom belongs to the Talipot palm (Corypha umbraculifera). The titan arum was originally discovered by an Italian botanist, Odoardo Beccari, in Sumatra in 1878. It thrives at the edges of rainforests near open grasslands. Though found in many botanic gardens around the world it is still indigenous only to the tropical forests of Sumatra. Due to its fragrance, which is reminiscent of the smell of a decomposing mammal,"History and Botany of the Titan Arum" from the Brooklyn Botanic Garden the titan arum is also known as a carrion flower, the "Corpse flower", or "Corpse plant" (in Indonesian, "bunga bangkai" - bunga means flower, while bangkai means corpse or cadaver; for the same reason, the same title is also attributed to Rafflesia which, like the titan arum, also grows in the rainforests of Sumatra).

The popular name titan arum was invented by the broadcaster and naturalist Sir David Attenborough, for his BBC TV series The Private Life of Plants, in which the flowering and pollination of the plant were filmed for the first time. Attenborough felt that constantly referring to the plant as Amorphophallus on a popular TV documentary would be inappropriate.