Hosokawa Tama　(細川玉, or Garasha ガラシャ, 1563–July 17, 1600) was a Japanese noblewoman, daughter of Akechi Mitsuhide. She married Hosokawa Tadaoki at the age of fifteen, and had two children.

In June of 1582, Akechi betrayed his lord, Oda Nobunaga. Afterwards, Tama became known as a "traitor's daughter." Not wishing to divorce her, Tadaoki accompanied her to a mansion in present Kyotango, Kyoto Prefecture, where the couple remained under house arrest until 1584. Tadaoki then took Tama to the Hosokawa mansion in Osaka, where she remained in confinement.

While in confinement, Tama befriended a Christian daughter of a prominent samurai. With the help of a Catholic missionary in Osaka, she was baptized in 1587 and received the Christian name Gracia. Tadaoki learned of her conversion and became enraged; he repeatedly demanded that she renounce her new religion, and even had Toyotomi Hideyoshi order her to do so, but Tama refused.

When Tokugawa's rival Ishida Mitsunari attempted to take her hostage, she ordered the family retainer Ogasawara Shosai to kill her; he and the rest of household then committed seppuku and burned the mansion down. Their sacrifice led to the Hosokawa family joining the war on Tokugawa's side.

A Catholic priest gathered Gracia's remains from the Hosokawa mansion and buried them in a cemetery in Sakai. Later, Tadaoki moved the remains to Sozenji , a temple in Osaka.

Gracia was canonized by the Catholic Church in 1862, and later used by James Clavell as the model for the character of Mariko in his novel Shogun.