**Kurdish Peshmerga **
We already know about them
Shia Armed Groups
Al-Sadr Fighters
Their activity while the US was present is well-known. After heavy confrontation with government forces, al-Sadr disbanded his army and reportedly turned it into a social and charitable network.
Still, al-Sadr kept an offshoot of the al-Mahdi Army, "Promised Day Brigades”, as an armed wing of his movement that continued to fight American forces in Iraq until the US’ withdrawal.
Al-Sadr, who joined the political process and whose followers became the second most powerful bloc in the Iraqi Parliament after the bloc of Maliki himself, has often disagreed with Maliki politically.
Asaib Ahl al-Haq (The League of the Righteous)
It is considered to be close to the Maliki faction. Asaib Ahl al-Haq was part of the al-Mahdi army until it split in 2006. After the US withdrawal, the group wanted to join the political process. Yet, its name has been in the news over the past two years with reports of its return to armed activity.
It is one of the Iraqi militia groups reportedly fighting in Syria. It has also been on bad terms with fighters loyal to al-Sadr in Baghdad. Fighters from the two groups have clashed with each other since the end of last year, prompting al-Sadr to accuse Maliki of backing the group since mid-2013, as the government needed support from loyal Sunni and Shia militias fighting ISIL in Anbar.
The website of the group says it is currently fighting along with government forces in Diyala, Anbar, and Samarra.
Kata’ib Hizbollah (The Battalions of the Party of God)
A militia group that has fought US forces in Iraq during occupation years, the group is thought to have been formed after the US-led invasion, from small Shia armed groups. It is also thought to be one of the main groups to continue fighting US forces in Iraq until their withdrawal in 2011. Rockets and roadside bombs were the main tactics used by the group that was designated a “terrorist” organisation by the US state department in 2009.
Kata’ib Hizbollah reportedly refused to lay down arms after the US forces withdrawal citing ongoing instability. The group says it is has been careful not to target any Iraqi forces or civilians during its attacks on US forces.
Kata’ib Hizbollah played a role in fighting along with Iraqi security forces in Anbar province since the end of last year and particularly in Fallujah. The group says it has formed “People’s Defence Brigades” to “defend the country and holy places” and fight ISIL. It lists among its local enemies Sunni groups such as the Naqshabandi Order and the 1920 Revolution Brigades.
aljazeera.com/news/middleeast/2014/06/mapping-out-iraq-fighting-groups-201462494731548175.html