Long story short, all Servants that will appear in the game, classified by class. Some of them have info of their stars as Servants, and the majority have info of which artist worked on them. There's also empty slots for future Servants (for example Nobunaga which is missing but I'm sure she will appear, and before you ask yeah it's a she). One thing we don't know from that list is who has a different gender than from the source they come from, so expect the unexpected.
There's tons of them, giving you a list here right now is kinda hard (and besides I would only be able to give you the names that are in Katakana). Fortunately someone did the job for me!
http://shinichameleon.tumblr.com/post/125782139590/fgo-all-over-100-playable-servants-are
http://blogs.nrvnqsr.com/entry.php/3273-GO-You!-The-Blacklist
Don't know if that's all of them. Huge spoilers btw, read at your own risk. Oh, and to break more people's heart, Iskandar (adult form) is 5*.
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Edit: Okay, here's what I understood. Only translated those without kanji, except when I already know who it is from the game itself. Feel free to fill the remaining "kanji" (all names are in the order they appear). I haven't done the ones that have no class assigned yet.
Spoiler, click to toggle visibilty
>Saber: Arturia, Arturia Alter, Arturia Lily, Nero, Nero Bride, Gawain, Siegfried, Mordred, Prototype Arthur, Caesar, Attila, Gilles de Rais, "kanji", Diarmuid, Lancelot, Astolfo.
>Archer: EMIYA, Gilgamesh, Robin Hood, Chiron, Atalanta, David, Prototype Gilgamesh, Orion & Artemis, Billy the Kid, Nicola Tesla, Euryale, Arash, Arjuna
>Lancer: Cu Chulaiin, Diarmuid, Vlad (EXTRA), Karna, Elizabeth, Benkei, Prototype Cu Chulaiin, Leonidas, Romulus, Brynhild, Scathach, "kanji", Hector?, Arturia Alter?, Enkidu, Arturia, "kanji", Perseus
>Rider: Medusa, Iskandar, Drake, Astolfo, Achilles, Georgius, Perseus, Edward Teach, Mary Read & Anne Bonny, Boudica, Ushiwakamaru, Alexander, Marie Antoinette, Saint Martha, Ozymandias, "kanji"
>Caster: Medea, Gilles de Rais, "kanji", Nursery Rhyme, Andersen, Avicebron, Shakespeare, Da Vinci-chan, Paracelsus, Charles Babbage, Mephistopheles, Amadeus Mozart, Zhuang Ling (Lord-El-Melloi II), Cu Chulaiin, Gilgamesh
>Assassin: Sasaki Koujirou (hero of France), Hassan of the Cursed Arm, "Hassan+kanji", "kanji", Jack the Ripper, Semiramis, Jekyll/Hyde, Stheno, Jing Ke, Sanson, Phantom of the Opera, Mata Hari, Carmilla, "another Hassan", EMIYA, Medusa (Child form)
>Berserker: Heracles, Lancelot, "kanji", Frankenstein, Spartacus, "kanji", Vlad (Apocrypha), Asterios, Caligula, Darius III, Kiyohime, Erik Bloodaxe, Tamamo Cat
>Shielder: Mashu
>Ruler: Jeanne, Amakusa Shirou, Jeanne Alter
>Alter Ego: Passionlip, Meltlilith, Kingprotea, Violet, Kazudrop
>Avenger: Angra Mainyu
