Toghrul (Mongolian: Тоорил хан Tooril han; Chinese: 脫里), also known as Wang Khan or Ong Khan (Ван хан Wan han; Chinese: 王汗; pinyin: Wáng Hán; died 1203), was a khan of the Keraites. He was the blood brother (anda) of the Mongol chief Yesugei and served as an important early patron and ally to Yesugei's son Temüjin, later known as Genghis Khan. The main source on his life is the Secret History of the Mongols.

"Wang Khan" was the name given to Toghrul by the Jurchen-led Jin dynasty of China; Wang means king or prince. During the 13th century, Toghrul was one of several Asian leaders who was identified with the legend of Prester John, but also King David, a brother to John. Although the Keraites converted to Nestorianism, a sect of Christianity, early in the 11th century there is no credible proof that Toghrul was himself Christian as Mongolian sources say nothing about his religion.

He was born around 1130, to Nestorian family of Keraites. His father was Cyriacus Buyruk Khan, the leader of Keraites. Toghrul had a very difficult youth. The Merkits captured him during his childhood and he was reduced to slavery. It is possible that he left the Merkit after being freed by a ransom or simply escaped. However, according to the Secret History, he was again abducted at the age of thirteen by the Tatars, who also took his own mother. When Toghrul returned to the Keraites later, his father was near death. Toghrul took his place and commanded the Keraites around 1165.

In order to eliminate potential rivals, he started by killing his brothers between 1165 and 1171. One of them, namely Erke Qara managed to escape and fled to the Naimans, who were a neighboring tribe to the west of the Keraites. The two other brothers, Buqa-Timur and Tai-Timur Taïshi were executed. However, Toghrul's success was brief because his uncle only known with the title Gurkhan overthrew him. Toghrul fled with his daughter and a handful of faithful. He tried to get the help of the Merkits to overthrow Gurkhan in turn, but their leader, Toqto'a Beki, refused despite the fact that Toghrul offered him his daughter because the Keraites were very numerous. Being unsuccessful, Toghrul went to see the father of Temüjin, Yesugei. He chose to help Toghrul because he had previously fought a battle with the Keraites against the Tatars. The Keraites were surprised when Yesugei attacked without having time to prepare. Despite the fact that the Keraites were much more numerous, their forces were dispersed throughout Central Mongolia. Toghrul resumed the command of the Keraites, and Gurkhan fled.

Toghrul was, like Jamukha, blood-brother of Temüjin. He led the coalition against Merkits when Temüjin's wife Börte was abducted in 1183, joined by his brother Jakha Gambhu, Jamukha and Temüjin. Two of the tribal chiefs, Dair Usun and Toqto'a fled the camp, probably informed by people who had seen the army move. The coalition easily won the fight that followed and about 300 Merkit perished. The chiefs distributed the booty among themselves and gave the Merkit wives to the warriors. The children became slaves. Börte was found later in the evening. Toghrul returned to the Kerait camp with his men, proud of an easy victory.

Temüjin, intending to attack the Tatar Confederation who had long caused him problems, including the murder of his father, asked for help from Toghrul in 1194; he willingly accepted, still satisfied with the victory he had had before. Toghrul's grandfather Marcus Buyruk Khan had also been assassinated by the Tatar, which gave him a similar reason to fight them. He joined Temüjin with a few thousand Keraites. The Jurkhin, a Mongolic tribe, were also invited, but declined the offer because they were somewhat hostile with the Borjigin tribe. They eventually found allies in Wanyan Xiang (完顏襄), minister of Emperor Zhangzong of the Jurchen-led Jin dynasty of China. The Tatars were considered by the Jurchens to be harmful and the opportunity was perfect to exterminate them. When the combined forces of Toghrul and Genghis Khan attacked the Tatars, they were caught in a vice as the Jurchen warriors behind them easily encircled the enemy tribe. The men were slaughtered, the women were taken as concubines and the children were adopted or became servants and slaves. Some thousands of Tatar who had resisted and then escaped entrenched themselves. This was the time when he was given the name Wang Khan (Chinese: 王汗; lit. 'King Khan').

Later that year he was overthrown by Erke Qara, whom he had not been able to assassinate and returned with the Naiman army. Many Keraites who were dissatisfied with the command of Toghrul probably also helped to drive Toghrul out. He fled to Yelü Zhilugu without even going to seek the help of Temüjin. He stayed there a year according to the Secret History. It was after leaving the Qara-Khitai that he finally decided to join Genghis Khan. According to Rashid al-Din, he would have reached Genghis Khan's encampment by 1196. Toghrul became his guest for about two years.

Living in exile, Toghrul was aided by Temüjin, who undertook an attack to the Merkits for a second time and gave a large part of the booty to Toghrul, who gifted it to different Kerait chiefs to consolidate allies with his tribe of origin. Temüjin then allegedly attacked a Kerait clan, the Tumen Tubegen, and a large part of the survivors became Toghrul's followers. The Keraites returned fully to Toghrul around 1198. The Naimans remained neutral and offered no help to Erke Qara because the Naiman people were then divided between two kings. Buyruq khan took the southern part and Tayang khan inherited the northern part of the Naiman lands. Erke Qara fled for the second time, this time to Buyruq khan. To reward the Keraites who had remained faithful to him, Toghrul ordered them to plunder the weakened Merkits for the third time. Important Merkits, including two sons of Toqto'a-beki, were captured while another was murdered. Meanwhile, Toghrul's brother, Jakha Gambhu became blood brothers with Temüjin.