The Alawites (12 percent of Syria's population)
The Assad family and the Syrian security forces are Alawite. Alawites identify as Shiite Muslims, but their religion includes aspects of Zoroastrian, ancient pagan, Christian and other beliefs. They believe in the divinity of Ali, the son-in-law of the prophet Muhammad.
After World War I, French colonial officials recruited ethnic minorities to fill government positions, and Alawites began to fill up the military's upper ranks. The Alawite air force officer Hafez Assad, Bashar al-Assad's father, staged a coup in 1970, and the Alawites have been in power since.
The Sunnis (about 60 percent)
Sunni Muslims form the majority in Syria. In Syria and Lebanon, they tend to support the rebels and oppose the Assad regime, and Syrian Sunnis have been subject to ethnic cleansing at the hands of the Alawite minority in recent months. While Alawi officers dominate the military leadership, the majority of troops are Sunni, according to the State Department.
Sunni Muslims have been gaining ground elsewhere in the region, as well -- the Arab Spring brought the Muslim Brotherhood to power in Egypt and Tunisia.
Greek Orthodox Christian (9 percent)
Syria's Orthodox Christians have so far shown support for keeping the Assad regime in place, if only because they fear the alternative.
"Many here fear revenge attacks against minorities, who helped buttress four decades of repressive rule by the Assad family, and the emergence of what they describe as a new dictatorship by the Sunni Muslim majority," the LA Times reported.
Kurd-Sunni (9 percent)
The Kurds say they want an end to Assad's regime, but they also fear that a potential future Sunni government might enact extremist policies.
There has been little cooperation between the armed Kurdish groups in the north and the Free Syrian Army, and their relationship seems to be one of mutual distrust, according to a recent report by the Washington Post's Babak Dehghanpisheh. But Kurdish fighters recently launched military action against Assad's forces, a move that rattled both Turkey and the Free Syrian Army.
The Kurds have also used the ongoing unrest as an opportunity to take control of at least four major cities in Syria.
Armenian-Christian (4 percent)
Much like the Orthodox Christians, Syria's 80,000 Armenians have generally supported Assad's government because of the relative stability it provided.
"It is natural that the majority of Armenians would support Bashar al-Assad, since they led safe and prosperous lives under his leadership, ethnic rights were fully protected, they have schools and churches," Arax Pashamyan, a specialist in Arab studies at the National Academy of Sciences of Armenia, told Armenia Now.
Armenians in Syria are less integrated than other groups and tend to avoid involvement in politics, according to Minority Rights Group International. They've taken a mostly neutral stance during the uprising.
The Druze (3 percent)
The Druze, who are ethnic Arabs, incorporate aspects of Islam, Judaism and Christianity into their belief system.
Like Syria's other religious minorities, they fear being disavowed in the event of a Sunni resurgence.
Many Druze live in Golan Heights, a territory on the Israel-Syria border annexed by Israel in 1967, and many believe the region will one day be returned to Syria. Because of that, many are careful about their criticisms of both the Assad regime and of
Israel, which provides Druze communities there with generous welfare benefits.