Catalysts

Servant Summoning catalyst
Saber Avalon
Avenger Avesta (summoned from a certain holy book)
Rider Similar background to Sakura and the desire to prevent the same sort of tragedy from happening to her
Lancer Earrings passed on in the Fraga family
Assassin Ties to Ryuudouji during life
True Assassin Assassin's body - this particular Hassan was summoned by having the same desire for eternity as Zouken did
Berserker Temple foundation of Hercules
Caster Unknown
Archer Rin's pendant
Archer (Gilgamesh) The fossilized remains of the skin of the very first snake that shed its skin
Rider (Iskandar) Mantle of Iskandar.