From the oil-rich Gulf states in the east to Morocco in the west, regimes throughout the Middle East could not help but worry they could see upheavals similar to Egypt's.
If it could happen in 18 days in Egypt, where Mubarak's lock on power had appeared unshakable for nearly 30 years, could it happen anywhere? Only a month earlier, Tunisia's president was forced to step down in the face of protests.
"Egypt is going to have a big, big impact around the region," said Salman Sheik, director of The Brookings Doha Center in Qatar. "It is — as it always has been — a bellwether for what happens elsewhere. It's wrong, though, to get into a count about what country could be next. The real impact is already being seen in reforms that are coming from countries feeling the pressure."
Zaki Bani Rusheid, a leading Islamist figure in Jordan, described "a new dawn, new stage" emerging.
"This is a new future painted by bloody hands of Egyptians and Tunisians that knocked on the doors of freedom."
Leaders across the region have made a variety of concessions and also tightened security.
Anti-government protests have erupted in recent weeks with demonstrators complaining of corruption, lack of services and rising prices. More are being planned.
Here's a look at what is expected in the Middle East.
Algerians have watched with fascination the revolts in Egypt, and opposition groups say they will defy a police ban and hold a protest march in the capital on Saturday, NBC News reported.
Algerians are angered by high unemployment, poor housing, high prices and corruption. They ask why they have not felt more benefit from the billions of dollars in oil and gas revenue the government spends on public projects.
President Abdelaziz Bouteflika, trying to stop mass protests from erupting, promised last week to allow more democratic freedoms, lift a 19-year-old state of emergency and generate more jobs.
Opposition groups are calling for street rallies Monday.
Bahrain is home to the U.S. Navy's 5th Fleet and the most politically divided in the Gulf. Majority Shiites have long alleged they face second-class status under the Sunni rulers. Last summer, the tiny nation was torn by clashes and riots after a wave of arrests against perceived Shiite dissidents.
On Friday — just hours before Mubarak stepped down — Bahrain's King Hamad bin Isa Al Khalifa granted each Bahraini family the equivalent of nearly $2,700 in an apparent bid to calm tensions.
Tehran is trying to stop opposition groups from seizing the moment with rallies linked to the Egyptian crisis, the BBC said. Iranian President Mahmoud Ahmadinejad told celebrations on Friday marking the 32nd anniversary of Iran's Islamic Revolution that Egyptian upheaval was an "Islamic awakening." This was a reference to the uprising that toppled the U.S.-backed Shah in 1979 and swept the Shi'ite Muslim clergy to power.
However, the pro-democracy Green Movement has called people to the streets Monday in solidarity with protesters in Egypt and Tunisia, The Wall Street journal reported. The call gained momentum on blogs and social networking sites, with over 30,000 people pledging to participate on one protest group's Facebook page.
Iran arrested several opposition activists and jammed signals of international broadcasters, the BBC said.
Libyan activists and the National Conference for Libyan Opposition have called for a Libyan "Day of Rage" on Thursday, NBC News reported.
Libyan leader Muammar Gaddafi has issued unprecedented warnings against any attempts to create chaos and instability in Libya, according to media reports.
In a traditional cornerstone of U.S. interests in the Mideast, a group of opposition activists said they asked the nation's king for the right to form a political party in a rare challenge to the absolute power of the ruling dynasty.
"You know well that big political developments and attention to freedom and human rights is currently happening in the Islamic world," the activist said in a letter to King Abdullah, who was one of Mubarak's staunchest supporters up until the end.
The nation's new prime minister, Marouf Bakhit, promised earlier this week to continue political reforms demanded by protesters who forced King Abdullah II to reshuffle the cabinet. Since the unrest in Tunisia and Egypt, Jordan's Muslim Brotherhood, their leftist allies and other protesters have demanded constitutional amendments to curb Abdullah's power in naming prime ministers and instead allow Jordanians to elect them by popular vote.
President Ali Abdullah Saleh — a key U.S. ally in office for more than three decades — bowed to pressure from protesters and announced he would not seek re-election in 2013 and would not try to pass power to his son. The opposition has yet to respond to his call to join him in a unity government. Saleh, a key U.S. ally against al Qaida, met with his top defense, political and security officials Friday night to discuss a plan to raise salaries for civil servants and the military — a second planned wage increase since last month, when Saleh planned a raise of about $47.
The move suggests that Saleh, a shrewd political survivor eyeing spreading unrest in the Arab world, is trying to ensure his forces would remain loyal in case of potential unrest in the impoverished Arabian Peninsula state.
The Gulf nation with serious political opposition outlawed any "gatherings, rallies or marches" after Friday prayers, said a report on the state news agency KUNA.
"Everybody should put the interests of the homeland above all considerations," said the statement by Kuwait, which has key U.S. military bases and is an important way station for the U.S. military withdrawal from Iraq.
It also showed how close any unrest in the region comes to U.S. military and political bulwarks — seen as a critical front-line alignment against Iran.
Iran's main Middle East ally has been showing some concessions to reformist fervor. This week, Facebook and YouTube were available for the first time in three years amid signs Damascus may be lifting its ban on the popular social networking websites that have helped energize and organize protests.