Rabbi Shmuel Halevi Kolin, also known as Kelin or Samuel Löw, was born in Kolín, Bohemia, in 5484 (1724) according to Hebrew Wikipedia, or around 1720 according to the Jewish Encyclopedia. He was the son of Rabbi Nathan Neta Halevi, of a family linked to Rabbi Nathan Neta Shapira of Kraków, author of Megaleh Amukot.

As a youth he was sent to study in Boskovice, Moravia, at the yeshiva of the town's rabbi, Rabbi Aryeh Yehudah Leib ben Menachem Mendel. Around 1738 he married Elkele, the rosh yeshiva's granddaughter, and remained at that yeshiva for nearly sixty years, raising thousands of students, while his wife supported the household through a small business.

He declined the rabbinates of Prague, Ofen (Buda) and Pressburg. Known for his prayers on behalf of the sick and for his asceticism, he devoted himself to charity, especially to marrying off and housing orphans, and established a fund to pay the teachers of children and another for bikur cholim. Hevrat Pinto also relates the story of a night-time "theft" of a Torah crown, by which he spared Rabbi Nathan Adler a police search, an episode said to have been witnessed by the Chatam Sofer, then Rabbi Nathan's student.

Works: Machatzit HaShekel, his main work, a super-commentary on the Magen Avraham to Shulchan Aruch Orach Chayim, printed in most editions; a Machatzit HaShekel on the Shach to Yoreh De'ah; novellae on many Talmudic tractates; and sermons.

He passed away in Boskovice on Thursday, Rosh Chodesh Nisan 5566 (March 20, 1806). He had asked for a simple tombstone without titles. His eldest son, Rabbi Binyamin Zeev Wolf Boskowitz, delivered his eulogy.