A mohel, or mo'el, is a Jewish ritual circumcisor who performs a brit milah ritual circumcision on the penis of a male who is to enter the Jewish covenant.
For Jews this is mandated, as it is prescribed in the Torah:
In the book of Genesis as a mark of the Covenant between God and the descendants of Abraham: "Throughout all generations, every male shall be circumcised when he is eight days old...This shall be my covenant in your flesh, an eternal covenant. The uncircumcised male whose foreskin has not been circumcised, shall have his soul cut off from his people; he has broken my Covenant" (Genesis 17:1-14),
In Leviticus: "God spoke to Moses, telling him to speak to the Israelites: When a woman conceives and gives birth to a boy...And on the eighth day, the flesh of his foreskin shall be circumcised."
In modern-day Judaism, circumcision is usually performed by a specially trained mohel, a specialist in circumcisions and the rituals surrounding the procedure. Biblically, the infant's father is commanded to perform the circumcision himself. However, as most fathers are not comfortable or do not have the training, they designate a mohel as a delegate. It is customary, that if possible, a mohel will perform his first circumcision on his own son, under the supervision of his own teacher.
The Reform and Conservative movements also train and accredit mohelim—they may even be medical doctors.