Joseph ben Solomon Ṭaiṭazaḳ (Hebrew: יוסף בן שלמה טאיטאצק), also referred to by the acronym MahaRITaTS, was a talmudic authority and kabalist who lived at Salonica in the 15th and 16th centuries. With his father and his brother he went in 1492 from Spain, his native land, to Salonica, where he became rabbi.
Life as Kabbalist 
Rabbi Tzayach was regarded as one of the most mysterious Kabbalists of the sixteenth century and one of the leading rabbinical figures within Jerusalem and Damascus. He discusses magic squares which allude to the highest and most concealed concepts, and their use within amulets. Many references can be found in writings of contemporary and leading Kabbalists, such as Rabbi Joseph Tirshom's manuscript (ca. 1550 CE) "Shoshan Yesod Olam" (The Rose, Foundation of the Universe), Rabbi Baal Shem Tov's (1537-1653 CE) Toledot Adam (Generation of Adam) and Rabbi Isaiah Horowitz's (1560-1630 CE) Sh'nei Luchot HaB'rit (Two Tablets of the Covenant) discusses the magic square in relation to the mysteries of creation. Joseph was a fervent adherent of the Kabbalah, in which he was well versed, and led an ascetic life. Elijah de Vidas, in his Reshit Ḥokmah (Sha'ar ha-Ḳedushshah, ch. vii), relates that, with the exception of Sabbath nights, Joseph for forty years never slept in a bed, but on a box, with his feet on the ground. With such a disposition to asceticism and mysticism it was but natural that Joseph should become enthralled by the Messianic vagaries of Solomon Molko, whom he supported while preaching at Salonica in 1529. Rabbi Aryeh Kaplan writes that "Rabbi Joseph Tzayach was apparently influenced by Abulafia's school of Kabbalah, and many ideas that he discusses seem to be taken verbatim from Abulafia's writings."
He was also considered one of the greatest Talmudists of his time, even Joseph Caro invoking his authority (Abḳat Rokel, §56). Among Joseph's disciples were Isaac Adarbi, Samuel di Medina, and Shlomo Halevi Alkabetz.
He was the author of the following works:
- Ben Porot, a commentary on Ecclesiastes (Venice, 1599)
- Leḥem Setarim, on the Book of Daniel and the Five Scrolls (ib. 1608), and on Psalms, Job, and Proverbs (Neubauer, Cat. Bodl. Hebr. MSS. Nos. 206, 2; 329; 969; 2270, 8; 3521)
- A commentary on the Sayings of the Fathers
- Responsa, some of which have been included in the writings of his contemporaries and pupils
- Notes on casuistical matters
- Commentaries on haggadic passages
- A treatise on the astrolabe (Neubauer, l.c. Nos. 834, 7, 10; 2080, 3; 2254, 8).
- According to Isaac Adarbi (Dibre Ribot, p. 64), Joseph was the author also of novellæ on Alfasi.
His Kabalistic works include:
- "Even Hashoham" -The Onyx stone
- "Tzeror Hachaim"- The Binding of Life
- "Tzafanat Paneach"
- "Sherit Yosef"- Remnant of Joseph
Jewish Encyclopedia bibliography 
- Gedaliah ibn Yaḥya, Shalshelet ha-Ḳabbalah, ed. Amsterdam, p. 49a;
- David Conforte, Ḳore ha-Dorot, p. 35a;
- Azulai, Shem ha-Gedolim, i.40;
- Giovanni Bernardo De Rossi, Dizionario, p. 314;
- Geiger, Zeitschrift, iii.285, No. 21;
- Moritz Steinschneider, Cat. Bodl. col. 1533;
- Heinrich Graetz, Gesch. ix.35, 236, 299.