The best man is the name given to the male assistant to the bridegroom at a wedding or marriage ceremony. Usually, the groom gives this honor to someone who is close to him, either a brother or his closest male friend.

In the context of a traditional American/British white wedding, the best man's duties typically include:

• helping the groom select and rent tuxedos and other formalwear
• planning the bachelor party with the help of the groomsmen
• getting the groom to the wedding on time
• supervising the groomsmen
• holding the bride's ring at the altar
• acting as a witness to the signing of the marriage license or register
• ensuring that the officiant of the wedding ceremony is paid
• giving a speech at the wedding, usually at the expense of the bride and groom, and thanking the bridesmaids

When the groom wishes to give this honor to a woman, she may be termed the "best woman" or "best person." The bride's equivalent of the best man is the maid or matron of honor.

In Uganda a best man does what is described above. He is also challenged to guide the newlyweds in ways of marriage. This means that ideally a best man must be married, preferably to one wife and should be in position to give sound, tried and tested advice. He should also be willing to have a listening ear to the new couple. If the new couple has an internal problem in their marriage, the responsibility is with the best man to guide them in what is best. A best man must be a confidant and be discreet about the details he hears from the new couple.