Answer by taking a quote from the following article:

Gulbuddin Hekmatyar was born in 1947 in Imam Sahib District of the Kunduz province, northern Afghanistan, a member of the Kharoti tribe of the Ghilji Pashtun. His father, Ghulam Qader, who migrated to Kunduz, is originally from the center of Ghazni province. Afghan businessman and Kharoti tribal leader Gholam Serwar Nasher deemed Hekmatyar to be a bright young man and sent him to the Mahtab Qala military academy in 1968, but he was expelled due to his political views two years later. From 1970 to 1972, Hekmatyar attended Kabul University's engineering department.

After the 9/11 attacks in the United States Hekmatyar, who had allegedly "worked closely" with bin Laden in early 1990s, declared his opposition to the US campaign in Afghanistan and criticized Pakistan for assisting the United States. After the U.S. entry into the anti-Taliban alliance and the fall of the Taliban, Hekmatyar rejected the U.N.-brokered accord of 5 December 2001 negotiated in Germany as a post-Taliban interim government for Afghanistan. As a result of pressure by the U.S. and the Karzai administration, on 10 February 2002 all the offices of Hezb-e-Islami were closed in Iran and Hekmatyar was expelled by his Iranian hosts.  The United States accuses Hekmatyar of urging Taliban fighters to re-form and fight against Coalition troops in Afghanistan. He is also accused of offering bounties for those who kill U.S. troops. He has been labeled a war criminal by members of the U.S.-backed President Hamid Karzai's government. He is also a suspect behind the 5 September 2002 assassination attempt on Karzai that killed more than a dozen people. In September 2002, Hekmatyar released a taped message calling for jihad against the United States. On 25 December 2002 the news broke that American spy organizations had discovered Hekmatyar attempting to join al-Qaeda. According to the news, he had said that he was available to aid them. However, in a video released by Hekmatyar 1 September 2003, he denied forming alliances with the Taliban or al-Qaeda, but praised attacks against U.S. and international forces.  On 19 February 2003 the United States State Department and the United States Treasury Department jointly designated Hekmatyar a "global terrorist." This designation meant that any assets Hekmatyar held in the USA, or held through companies based in the U.S., would be frozen. The U.S. also requested the United Nations Committee on Terrorism to follow suit, and designate Hekmatyar an associate of Osama bin Laden. In October 2003, he declared a ceasefire with local commanders in Jalalabad, Kunar, Logar and Surobi, and stated that they should only fight foreigners.  In May 2006, he released a video to Al Jazeera in which he accused Iran of backing the U.S. in the Afghan conflict and said he was ready to fight alongside Osama bin Laden and blamed the ongoing conflicts in Palestine, Iraq and Afghanistan on U.S. interference. In September 2006, he was reported as captured, but the report was later retracted. In December 2006, a video was released in Pakistan, where Gulbuddin Hekmatyar claimed "the fate Soviet Union faced is awaiting America as well." In January 2007 CNN reported that Hekmatyar claimed "that his fighters helped Osama bin Laden escape from the mountains of Tora Bora five years ago." BBC news reported a quote from a December 2006 interview broadcast on GEO TV, "We helped them [bin Laden and Zawahiri] get out of the caves and led them to a safe place."

Have there been any assassination attempts?
He is also a suspect behind the 5 September 2002 assassination attempt on Karzai that killed more than a dozen people.