You don't need to reserve a color, just check this list before you post your profile.
COLOR COUNT:
151 total ; 139 not counting custom/code colors ; 120 not including customs and colors deemed too light to use
78 non-custom colors are used up.
42 colors are left. Feel free to inform me of new colors to add to this list.
You can also use custom colors. 12 custom colors are currently being used.

* indicates that I do not really recommend using these colors, as they are quite light, and hard to see unless on a dark background. So unless you plan on using the document format on all your posts, I suggest you stray away and use one of the many many many other colors.



Bisque
Peach Puff
Blanched Almond
Moccasin
Navajo White
Wheat
[Burly Wood] Layla Alexander, Ravenclaw, 1st year
[Tan] Elvis [Barrett] McKay, Hufflepuff, 3rd year
Sandy Brown
[Peru] Severus Snape, Faculty, Potions Master and Head of Slytherin
Chocolate
Saddle Brown
[Sienna] Adela Heid, Ravenclaw, 6th year
Brown
Maroon
[Dark Red] Jane Driscoll, Gryffindor, 5th year
[Fire Brick] Eriol Turner, Gryffindor, 7th year
[Indian Red] Minerva McGonagall, Faculty, Transfigurations Professor and Head of Gryffindor
[3CD4F5B] Roxanna Osbourne, Ravenclaw, 7th year
[#B52652] Madeline Wickliff, Ravenclaw, 4th year
[Light Coral] -reserved- Fatima Mastriani, Gryffindor 7th year
Dark Salmon
Salmon
Light Salmon
[Coral] George Weasley, Gryffindor, 2nd year
Tomato
Crimson
[#CC0000] Angelica Carrington-Lowe, Ravencalw 6th year
Red
[#FF4422] Ramsey Castillo, Slytherin 5th year
Orange Red
[Dark Orange] Fidelious Violino [Fig] Gryffindor, 3rd year
[Orange] Leigh Guidry, Gryffindor, 3rd year
[#FFC524] Shaynne Randle [Hollywood], Hufflepuff, 5th year
[Gold] -reserved- Laurence Craig, Gryffindor 6th year
Yellow
Light Goldenrod Yellow*
Lemon Chiffon*
Cornsilk*
Ivory*
Floral White*
Seashell*
Old Lace*
Linen*
Antique White
Papaya Whip
Light Yellow*
Beige*
Pale Goldenrod
[Khaki]Brady Allen the IV, Slytherin, 2nd year [u/c]
[Dark Khaki] -reserved- Kiyoshi Mishima, Slytherin 7th year
[#E8A317] Sun Bae, Gryffindor, 4th year
[Goldenrod] Natalie Summers, Gryffindor, 1st year
[Dark Goldenrod] William Raines, Gryffindor, 7th
[Olive] Oliver Wood, Gryffindor, 4th year
[Olive Drab] Dominic Gellar, Hufflepuff, 7th year
[Dark Olive Green] Raphael Stark, Slytherin, 5th year
[Yellow Green] Aidan Reese, Slytherin, 7th year
[Green Yellow] Amanda Lilliquist, Slytherin, 7th year
[Chartreuse] Juliet Setterfield, Gryffindor 6th year
Lawn Green
Lime
[Medium Spring Green] Drake Alexander, Ravenclaw, 5th year
Pale Green
Light Green
Honeydew*
[Lime Green] Melanie Parks, Slytherin, 4th year
[#339922] Kevin Jameson, Ravenclaw, 5th year
Forest Green
Green
Dark Green
[Dark Sea Green] Eleanor Davis, Hufflepuff, 6th year
[Sea Green] Emmit Yates [Glenn], Gryffindor, 7th year
[Medium Sea Green] Nathaniel Mason, Ravenclaw 5th year
[Medium Aquamarine] Julia Lavigne, Ravenclaw, 3rd year
[Aquamarine] Lolita Doerity [Dotey], Slytherin, 3rd year
Aqua
Cyan
[Turquoise] Brianna Porter, Gryffindor, 1st year
[Medium Turquoise] Tracey O'Donnell, Ravenclaw, 4th year
[Dark Turquoise] Lorraine Shaw, Gryffindor, 7th year
Light Sea Green
Teal
[Dark Cyan] Zaidin Berkeley, Ravenclaw, 7th year
[Cadet Blue] Athenadora Zakarova, Hufflepuff, 3rd year
[Steel Blue] Masika Het-Heru, Ravenclaw, 6th year
[#024793] Skylar Martin, Slytherin, 6th year
[#003399] Cecilia Rigby, Slytherin 6th year
Cornflower Blue
Mint Cream*
Azure*
Light Cyan*
[Pale Turquoise] Myranda Halliwell, Ravenclaw, 2nd year
[Powder Blue] Johanna Mattson, Slytherin, 3rd year
[Light Blue] Junko Saehara, Slytherin, 5th year
Sky Blue
[Light Sky Blue] Azula Tanaka, Slytherin, 6th year
Light Steel Blue
[Deep Sky Blue] Richard Samuels [Rick], Hufflepuff, 4th year
[Dodger Blue] Mackenzie Alexanders [Mac/Kenzie], Hufflepuff, 4th year
[Royal Blue] Emilie Del'Cour'D'Amor, Faculty, Defense Against the Dark Arts Professor
Blue
[Medium Blue] Cameron Rivers, Ravenclaw, 1st year
[Navy] Quinton Zsarcaspian, Hufflepuff, 6th year
[Dark Blue] Zaccheus Dane, Slytherin, 3rd year
[Midnight Blue]Maddox Langston Kingsley, Ravenclaw, 7th year
[Dark Slate Blue] Robert McClellan, Slytherin, 3rd year
[Slate Blue] Jasper Jennings [Moochie!], Ravenclaw, 4th year
Medium Slate Blue
Medium Purple
[Dark Orchid] Bailey Ann Thompson, Gryffindor, 1st year
Blue Violet
[Dark Violet] Skander McHale, Gryffindor, 5th year
[Purple] Julian MacGregor, Hufflepuff, 4th year
[Dark Magenta] Alanis Jensen, Ravenclaw, 3rd year
[Indigo] Elayne Harkin, Hufflepuff, 3rd year
[Medium Orchid] Lyra Nafisa Winner, Slytherin, 4th year
[#CC00FF] Amber Wolfsten, Hufflepff, 2nd year
[Orchid] Ryan Martin, Ravenclaw, 7th year
Violet
[Plum] Rosaline Windsor, Ravenclaw, 5th year
Lavender
[Thistle] Andromeda Reinhardt, Hufflepuff, 5th year
Lavender Blush *
Misty Rose
[Pink] Elizabeth Spelling [Izzy] , Slytherin, 1st year
[Light Pink] Cordelia Jones, Slytherin, 2nd year
[Rosy Brown] Shawn Porter, Hufflepuff, 2nd year
[Pale Violet Red] Mary Perison, Hufflepuff, 4th year
[Hot Pink] Ophelia Ozma, Ravenclaw, 6th year
[Deep Pink] Adelaide Burkley [Alice!] Gryffindor, 5th year
Fuchsia
Magenta
[Medium Violet Red] Olivia Zsarcaspian, Slytherin, 4th year
Black
Dim Gray
Gray
Dark Gray
[Silver] Rain Larks, Slytherin, 6th year
Snow*
White*
Ghost White*
White Smoke*
Gainsboro
Light Grey
[Light Slate Gray] Rainbow Peterson, Hufflepuff, 7th year
[Slate Gray] Jin Choi, Hufflepuff, 2nd year
Dark Slate Gray