The Horowitz Rabbinical Family
A substantial number of tested R1a-Y2619 Ashkenazi Levite men have close Y-DNA STR or SNP matches with direct male descendants of men surnamed Horowitz (or a derivation thereof), including three men who believe that they are ninth-generation descendants of Rabbi Shmuel Shmelke Horowitz of Tarnow, who lived in the 17th century (and was the great grandfather of the much better known Shmuel Shmelke Horowitz of Nikolsburg (Mikulov) (1726-1771)).
The Horowitz rabbinical family’s direct male line traditionally traces back nearly 1,000 years, with a gap of two or three generations (and Horowitz family tradition further traces the family’s roots back to Samuel Halevi, the prophet and judge who anointed Kings Saul and David 3,000 years ago). According to the Horowitz family’s genealogical tradition, the family’s direct male ancestor is Shem Tov Halevi of Girona, who lived in the 11th century, and over the next four centuries the family’s direct male ancestors moved between Provence (now in France) and Aragon (now in Spain). (However, a 2016 article by Avrohom Marmorstein questions the Horowitz tradition of ancestry from Spain, asserting that it was not until the late 19th century that Iberian roots were claimed for the Horowitz rabbinical family.)
In the 1470s, the family moved to the shtetl of Horovice, Bohemia (now in the Czech Republic) (the name Horowitz designates an origin in Horovice), near Prague; soon thereafter, the family moved to Prague. Rabbi Isaiah ben Moshe Asher Halevi Horowitz, also known as Zalman Horowitz (@1440 – 1515), who lived in the village of Horovice and, later, in Prague, had seven sons.
Within a century or two, members of the Levite Horowitz rabbinical family had moved to Poland, Lithuania, Russia, Belarus, Ukraine, and throughout the Austro-Hungarian Empire, serving as rabbis in, inter alia, Prague, Cracow, Vienna, Hamburg, Nikolsberg, Tikocin, and Brody. See generally S. Gurevich, Gurevich, Gurovich, Gurvich, Gorvich, Gurvitz, Horowitz and Others: History of a Great Family (Haifa, 1999, ISBN 965-222-971-7).
Some direct male descendants of the Horowitz rabbinical family retained the Horowitz surname through the centuries. Based upon personal genealogical records, as supported by Y-DNA evidence, some direct male descendants of the Horowitz rabbinical family adopted other surnames.
Conversely, it was not uncommon for men who were not direct male descendants of the Horowitz rabbinical family (such as sons-in-law of a Horowitz) to adopt the Horowitz surname; this practice is reflected by the fact that there are a significant number of Horowitzes who are not R1a-Y2619 Ashkenazi Levites. Similarly, men from Horovice who were not members of the Horowitz rabbinical family may have adopted the surname Horowitz, as a reference to their geographical origins.
Y-DNA analysis, coupled with paper genealogy, may allow us to tie some closely related R1a-Y2619 Ashkenazi Levites to the lines of the sons of Rabbi Isaiah ben Moshe Asher Halevi Horowitz (@1440 – 1515), the founder of the Horowitz rabbinical family.
The analysis to date suggests that some of the known Horowitzes with test results are descended from Rabbi Shmuel Shmelke Horowitz (? – 1694), a descendant of Rabbi Isaiah ben Moshe Asher Halevi Horowitz through his son Aharon Meshullam Zalman Horowitz, also known as Zalman Munka (1470 – 1545); the R1a-Y2619 Ashkenazi Levite men whose test results are close to the R1a-Y2619 Ashkenazi Levite mode (especially those with the STR marker value of DYS495=16) are more likely to share an MRCA with these members of the Horowitz family in, perhaps, the 13th century to the 17th century.
The genealogy of the Horowitz rabbinical family has been extensively researched over the years.
Dr. Edward Gelles has kindly allowed us to post: (1) the Horowitz rabbinical family's claimed line of descent to the year 1000 in Gerona, Spain; (2) a tree showing the believed relationships of the ancestral line of the Horowitz rabbinical family to other prominent Jewish families in Spain and France from the 11th through 14th centuries; and (3) a tree showing branches of the Horowitz rabbinical family after that family's move to Horovice, near Prague, in the 1470s. For further information, see E. Gelles, Meeting my Ancestors (Shaker Publishing, Maastricht, 2011), E. Gelles, Family Connections: Gelles-Horowitz-Chajes (Shaker Publishing, Maastricht, 2008), and Dr. Gelles’ volume of essays, The Jewish Journey: A Passage Through European History.
The late Michael Honey prepared a very detailed family tree for the Horowitz rabbinical family starting in 1400 and including some branches through the present day.
In his book Gurevich, Gurovich, Gurvich, Gorvich, Gurvitz, Horowitz and Others: History of A Great Family (Haifa, 1999, ISBN 965-222-971-7), Shlomo Gurevich of Hoshaya, Israel provides a detailed history of the family.
On the Jews of Frankfurt DNA Project page, Janet Billstein Akaha has posted a "condensed" Horowitz lineage going back to the 12th century in Barcelona.
However, a 2016 article by Avrohom Marmorstein questions the contention that the Horowitz rabbinical family has Iberian roots, asserting that it was not until the late 19th century that a Spanish connection was asserted for members of the Horowitz rabbinical family. In this regard, it should be noted that a related Horowitz tradition - that a Horowitz ancestor was the brother of a Benveniste ancestor and an Epstein ancestor - is not supported by the Y-DNA evidence to date (currently, no Benvenistes, and only one of many Epsteins to have done Y-DNA testing, are known to be members of the R1a-Y2619 Ashkenazi Levite cluster to which known descendants of the Horowitz rabbinical family belong).
Tomb of Isaiah Halevi Horowitz (the Shelah), Tiberias Ancient Cemetery
THE HOLY SHL”A
our teacher Rabbi YESHYAHU son of Rabbi AVRAHAM HaLEVI HOROWITZ
blessed be the memory of the Tzadik
Served as Head of Great Rabbinical Courts in Europe
made ALIYA from Prague to The Land of Israel on 5381 
served as Rabbi of communities in Jerusalem, Safed and Tiberias
wrote “TWO TABLETS OF THE COVENANT” and other books
NIFTAR in Tiberias on the 11th of Nissan 5390 [March 14, 1630]
May His Soul be Bound with The Living
Photograph and translation courtesy of Meir G. Gover
Tomb of Shmuel Shmelke Segal Ish Horowicz, Jewish Cemetery of Tarnow, Poland
Woe to us, we have lost the crown
over our head, our beloved
elder Rabbi who acquired
wisdom, Shmuel Shmelke
Segal [staff of Levites], son of the great light Rabbi
Yehoshua the tall Halevi
Ish-Horowicz, blessed be the memory of the Tzadik, went
to a better world on Wednesday, The 1st of the month
of Elul. [19 August]
Shmuel may he rest in peace, today
40 days [after his death] the year of תנו'ה 5456. .
May His Soul Rest With The Living
Translation courtesy of Meir G. Gover