Merchant

Merchants are citizens that sell and buy things on the towns.

Assassin's Creed
The role of merchants on AC1 is mostly provide a atmosphere, but they also make for some escape options and way of dealing with enemies {throwing one on a tend immediatelly disposes of him}}. On the PC version, there are also secondary missions which you must destroy a number of market tends before the timer runs out.

Assassin's Creed II
On AC2, the role of merchants is much improved. Aside from the mentioned above, the player can now buy stuff from them, ranging from weapons to armor.