"D'you think we've got nothing better to do in Potions than listen to Snape?"
     -- Ron Weasley

Q: Have any of the Hogwarts professors had spouses?
JKR: Good question - yes, a few of them but that information is sort of restricted - you'll find out why. (CR)

At Hogwarts, a staff of about fourteen teachers handles classes for hundreds of students. Any way you look at it, that's a lot of classes for a few staff members. There are exactly the same number of female as male staff members at Hogwarts (or there were, as of the 1993-94 school year).

Albus Dumbledore
Headmaster (c.1970s - present)
Transfiguration c.1940s 

Minerva McGonagall
Transfiguration Teacher
Deputy Headmistress
Head of Gryffindor House

Severus Snape
Potions Master
Head of Slytherin House

Rubeus Hagrid
Care of Magical Creatures (September 1993-present)
Keeper of the Keys and Grounds

(Filius) Flitwick
Charms teacher
Head of Ravenclaw House
(first name is not certain)

Sinistra
witch?
Astronomy Teacher

Sibyll Trelawney
Divination teacher

Binns
wizard, the only ghost teacher
History of Magic teacher

Vector
witch
Arithmancy teacher

(Pomona)Sprout
witch
Herbology
Head of Hufflepuff House
first name not certain

Madam (Rolanda) Hooch
Quidditch referee
Flying teacher
first name not certain

(Quirenius) Quirrell
Defense Against the Dark Arts
before 1990-1991, 1991-2
first name not certain

Gilderoy Lockhart
Defense Against the Dark Arts 
1992-3

Remus Lupin
Defense Against the Dark Arts 
1993-4

Alastor Moody
Defense Against the Dark Arts
1994-5?
The real Alastor "Mad-Eye" Moody did not serve on staff, although this was not discovered until June, 1995. The teacher everyone thought was Moody was actually Barty Crouch Jr. in disguise.

Kettleburn
Care of Magical Creatures 
through  spring 1993, when he decided to retire and spend time with his remaining limbs

Grubbly-Plank
witch
temporary - Care of Magical Creatures  (January, 1995)

Argus Filch
caretaker

Madam Poppy Pomfrey
School nurse

Madam Irma Pince
librarian

unknown teachers for Ancient Runes and Muggle Studies

former staff members
Apollyon Pringle - caretaker (Molly Weasley's era)
Ogg - Groundskeeper (Molly Weasley's era)
Armando Dippet (Headmaster c. 1940)

see also: academics

Notes on the ratio of male to female staff members at Hogwarts:
(Thanks to Tennant Stuart whose excellent post on alt.fan.harry-potter was a great help)

Rowling stated in an interview with Radio CBC This Morning, October 23, 2000:

(I)n fact, if you look at the Hogwarts' staff - I had this discussion with someone the other day - it is exactly 50/50. Although it is true that you do have a headmaster as opposed to a headmistress, but that has not always been the case. As you will find out, there have been equal numbers of headmistresses. 

TEACHING STAFF ONLY

WOMEN	MEN
Madam Hooch (Quidditch) Minerva McGonagall (Transfig)  Professor Sinistra (Astronomy)  Professor Sprout (Herbology) Sibyll Trelawney (Divinations) Professor Vector (Arithmancy) Unknown teacher (MS/AR)*	Professor Binns (History of Magic) Albus Dumbledore (Headmaster) Professor Flitwick (Charms) Hagrid/Kettleburn (Care of Magical Creatures) Severus Snape (Potions) Quirrell/Lockhart/Lupin/Moody (DADA) Unknown teacher (MS/AR)*

* Unknown teachers for Muggle Studies and Ancient Runes, presumably one male and one female to keep the lists balanced.

If Hooch is not considered staff, we could add Grubbly-Plank to that female column to make it work out. Either way, we must assume that Sinistra is a witch in order to make the numbers work out. This ratio will change when the new female Defense Against the Dark Arts professor takes over in OP.