There are many forms of honorifics that are used when addressing the members of the nobility, clergy, or royalty, mostly in countries that are monarchies. These include "Your Majesty" and "Your Highness", which are often used when speaking with royalty, or "My lord/lady" to address a peer other than a Duke, who is referred to as "Your Grace".
Some honorifics distinguish the sex of the person being referred to. Some titles of the nobility and of professional honorifics, such as Doctor or General, are not gender specific because they were traditionally male-only professions, and women have simply adopted the associated titles.
Sir: for men, formally if they have a British knighthood or if they are a Baronet, or generally as a term of general respect or flattery. Equivalent to "Madam" (see below). Also used in some Secondary Schools ; most tend not to call male teachers "Mr ___", but rather "Sir".
Madam or Ma'am (pronounced to rhyme with "ham" in some American accents or "harm" in a British accent): for women, a term of general respect or flattery. Equivalent to "Sir" (see above).
Both "Sir" and "Madam" are commonly used by workers performing a service for the target of the service, e.g. "May I take your coat, Ma'am?"
Lord: for male viscounts, earls, and marquesses, as well as some of their children. (Style: Lordship or My Lord)
Lady: for female viscounts, earls, and marquesses. (Style: Your Ladyship or My Lady)
Prof.: (Professor) used generally for people teaching at the college level in the US. Persons holding academic research PhD degrees in the US are more likely to be referred to as "Prof" over "Dr" to prevent confusion with the common meaning of "Doctor" (because teaching at the college level generally requires a PhD degree). In Commonwealth countries, Professor is the highest rank reached in academia with or without a PhD.
Br: (Brother) for men generally in some religious organizations; in the Catholic Church and Eastern churches, for male members of religious orders or communities, who are not Priests.
Sr: (Sister) Nun or other religious sister in the Catholic Church; for women generally in some religious organizations, such as the Mormons. Sometimes informally abbreviated as 'Sis'.
Fr: (Father) for priests in Catholic and Eastern Christianity, as well as some Anglican or Episcopalian groups; Generally equivalent to 'Reverend' (see below).
Rev.: (Reverend) used generally for members of the Christian clergy regardless of affiliation, but especially in Catholic denominations. Equivalent to 'Father' (see above).
Pr: (Pastor) used generally for members of the Christian clergy regardless of affiliation, but especially in Protestant denominations. Equivalent to 'Reverend' (see above).
Elder: (Elder) used generally for male missionaries of The Church of Jesus Christ of Latter Day Saints and for members of the adult leadership known as the general authorities. Although most all male adults of the LDS church are Elders, the title is reserved for the prior mentioned groups.
Adv. or Counsellor: (Advocate) for Lawyers and Advocates in Scotland; in South Africa only the former is used. In the United Kingdom, "Cllr." can be used for an elected local councillor, a political position.
Mx. (Mix) has been suggested as a gender-neutral alternative to more common honorifics.