Rosh yeshiva (Hebrew: ראש ישיבה; pl. Heb. Roshei yeshiva; Yeshivish: Rosh yeshivahs), is the title given to the dean of a Talmudical academy (yeshiva). It is made up of the Hebrew words rosh — meaning head, and yeshiva — a school of religious Jewish education. The rosh yeshiva is required to have a vast and penetrating knowledge of the Talmud and the ability to achieve a level of mastery of his material and an ability to analyse and present new perspectives, called chidushim, (novellae) verbally and often in print.
The primary role of the rosh yeshiva is not simply to be the dean, but is generally to say the highest level lecture in the Yeshiva, which is usually a program of at least two years. Students who have studied in a Yeshiva are generally known as students of the Rosh Yeshiva, as his lecture is the one in which they usually attain their method of Talmudic analysis and critical reasoning, and this method is based on the particular style of that Rosh Yeshiva. In addition, since Yeshivas play a central role in the life of certain communities within Orthodox Judaism, the position of Rosh Yeshiva is more than just his position within the yeshiva. A Rosh Yeshiva is often seen as a pillar of leadership in extended communities. In Hasidic Judaism the role of Rosh Yeshiva is secondary to the Rebbe, who is head of the Hasidic dynasty that controls it. In many Hassidic sects, the Rosh Yeshiva of a school will be the son or son-in-law of the Rebbe, the assumed heir of the Rebbe. However the role that yeshivohs have within Hasidic communities is not nearly as important as it is in Lithuanian Jewish, or Litvishe, communities. Hassidic students usually get married at the age of 18, which in most cases is the end of their yeshiva education, while students in the Lithuanian Jewish communities continue to study, at a minimum till they get married starting at age 23, and the vast majority continue their studies after marriage. As a result the role that a Rosh Yeshiva plays in Lithuanian Jewish communities is much more important than in the Hassidic ones.
Yeshivas continue the scholarly traditions of the sages of the Mishnah and Talmud who often headed academies with hundreds of students. In the Talmudic academies in Babylonia the rosh yeshiva was referred to as the Reish Metivta in Aramaic and had the title of Gaon.
General role 
The general role of the rosh yeshiva is to oversee the Talmudic studies and practical matters. The rosh yeshiva will give the highest shiur (class). He is also the one to decide whether to grant permission for students to undertake classes for rabbinical ordination, known as semicha.
Rosh yeshiva dynasties 
Depending on the size of the yeshiva, there may be several rosh yeshivas, sometimes from one extended family. There are familial dynasties of rosh yeshivas, for example the Soloveitchik, Finkel, Feinstein, Kotler and Kook families, which head many yeshivas in the United States and Israel.
Famous rosh yeshivas 
The following is a list of some famous rosh yeshivas:
Current rosh yeshivas 
Role of mashgiach ruchani 
The personal and ethical development of the students in the yeshiva is usually covered by a different personality, known as the mashgiach or spiritual supervisor. This concept, introduced by the Mussar movement in the 19th century, led to perfection of character as one of the aims of attending a yeshiva. One typical and influential mashgiach was Rabbi Eliyahu Eliezer Dessler.