Gholam were made by Aginor during the War of Power to assassinate Aes Sedai. They are immensely strong, have no bones, and are able to squeeze through incredibly small spaces. Only six were made, three male and three female, as the Forsaken were wary of an assassin designed to target channelers.
Gholam are immune to the One Power and most known weapons. They can detect a channeler at fifty paces and someone holding the One Power from even further. From several miles away gholam are able to feel use of the One Power and True Power as an itch akin to that experienced by the Myrddraal.
Gholam live on fresh blood, generally rending their victims limb from limb or tearing their throats out before feeding. Their preferred prey are channelers, as they receive a sense of euphoria when they take the life of one who can channel.
Furthermore, gholam are incredibly resistant to harm. They are completely immune to conventional weapons and weaves directed at gholam dissolve. However, they may be indirectly harmed by weaves that are directed at other objects or at the surrounding environment. At the present time, the foxhead medallion worn by Matrim Cauthon is the only thing known to have hurt a gholam.
The final gholamEdit
It looks like a man, slender with sandy hair and unremarkable features. It has a scar on its cheek where Mat hit it with his foxhead medallion.
Ebou Dar Edit
The gholam began its killing spree with Herid Fel, a knowledgeable resident of Rand al'Thor's school in Cairhien who had been helping Rand figure out what to do about the seals to the Dark One's prison.
It was then sent to Ebou Dar to attempt to stop the recovery of the Bowl of the Winds. There, it attacked a number of Wise Women, Elayne Trakand, Mat, and his Redarms. It fled after touching Mat's medallion, which appeared to burn its cheek.
It demonstrated independent thought, as it had been ordered to track down Nynaeve al'Meara and Elayne but it wanted revenge on Mat for hurting it. It attacked Mat again in Ebou Dar, and was again forced to retreat when Mat defended himself with the medallion and Noal Charin came to his aid. It remained in Ebou Dar killing arbitrary people for their blood. In its hunt for Mat, it also killed Queen Tylin Quintara Mitsobar after finding her in chambers where Mat had left her tied up when he left Ebou Dar.
After the Band of the Red Hand set up camp a league outside Caemlyn, the gholam returned, now under orders to kill Mat and those close to him, like Thomdril Merrilin, Noal, and Tuon. It left a trail of dead citizens in Caemlyn as it tracked him, finally coming to wait for him at the Band's camp, where it killed Lopin before attacking Mat again. It would have succeeded if not for the aid of Teslyn Baradon. It was eventually forced to flee after the rest of the Redarms were alerted. 
Soon afterward, Mat confronted the gholam for one final time, intentionally luring the creature to him in the streets of Caemlyn. He surprised the gholam with two extra foxhead medallions, lesser copies created by Elayne, and backed the Shadowspawn into a house. Then he used the three medallions to dispose of the gholam by corralling him into a gateway leading to the endless void used for Skimming, which had been carefully placed beforehand by Sumeko Karistovan. Its exact final fate inside of the void is unknown although it is assumed that it will keep falling forever. 
The word gholam is likely a reference to golem, an animated anthropomorphic being made of inorganic matter that appears in Jewish mythology and popular culture.