Cashura

Cashura (カーシュラ) is a character who appears in Fate/strange fake. He is a magus who works for the US government and summoned Saber in the False Holy Grail War.

Fate/strange fake
Cashura tried to summon King Arthur for the False Holy Grail War, but was killed by Assassin, leaving the summoning incomplete. Because of the incomplete summoning, Richard I was summoned instead.