Who is Caesar Spada?

From the text:

The pope and Cæsar Borgia first found the two future cardinals; they were Giovanni Rospigliosi, who held four of the highest dignities of the Holy See, and Cæsar Spada, one of the noblest and richest of the Roman nobility; both felt the high honor of such a favor from the pope. They were ambitious, and Cæsar Borgia soon found purchasers for their appointments. The result was, that Rospigliosi and Spada paid for being cardinals, and eight other persons paid for the offices the cardinals held before their elevation, and thus eight hundred thousand crowns entered into the coffers of the speculators.