Melocactus matanzanus, common name dwarf Turk's-cap cactus or Turk's-cap cactus, is a cactus in the genus Melocactus of the family Cactaceae. The epithet matanzanus is derived from the Cuban province of Matanzas.
Melocactus matanzanus is a perennial fleshy globose plant. It can reach a height of and a diameter of . On the bright green body there are 8–9 (or more) ribs. The thorns are brownish-gray or white. The central spine is up to long, while the 7 to 8 radial spines are long.
When the plant has reached a certain age it shows at the growing tip a cephalium (hence the common name of "Turk's Cap"), a globose structure covered with reddish-brown bristles. This structure, where the flower buds will form, reaches a height of up to and a diameter of . The flowers are carmine, about long.
This plant is native to the north-central area of Cuba. It is a popular and desirable species throughout the world as an ornamental plant.