Edit: Hmm, I guess officially he is consider as Saber xD But it turns to 'Saver' when romanized.
Fate/Prototype is a short OVA included in Carnival Phantasm, the original story of FATE. In here, Saber is a man, and Shirou is supposed to be a girl named Ayaka. But of course the series would get all bishoujo that way <3
It's really short, but a few minutes staring at Saber (or really, Saver) was epic, especially his fight with Gilgamesh. He's much kinder and cuter than female Saber.
Saber + Fate/Prototype (c) TypeMoon