In the aftermath of bin Laden's killing, more than a dozen extremist groups -- some directly affiliated with al Qaeda -- released statements mourning the terror leader's death and promising vengeance against the West.
The one al Qaeda branch that senior U.S. officials have called the most serious threat to the American homeland, al Qaeda in the Arabian Penninsula, released a video earlier this month in which one of their leaders said the fight would turn so bloody America would "wish for the days of Osama."
"Do not dismiss this battle so easily, and give your people false hope that if you kill Osama that it is over," promised Nasir al-Wahishi, a leader of the Yemen-based AQAP. "What is waiting for you is far greater and more dangerous, and you will then count your regrets, wishing for the days of Osama."
Al Shabaab, a Somali-based al Qaeda affiliate, also promised to avenge bin Laden's death in a rare press conference outside Mogadishu last week.
"We are sending a message to [U.S. President Barack] Obama and [Secretary of State] Hillary Clinton that we will avenge the death of our leader Sheikh Osama bin Laden very soon," Omar Hammami, the Alabama-raised jihadi also known as al-Amriki or The American, told reporters according to Agence France Presse.
The same group also made a personal threat against President Obama's 88-year-old grandmother, who lives in Kenya, Kenyan police said.
Similar messages from various other groups have appeared on jihadist websites and online discussion forums in the days following the death of America's most wanted man.
ABC News' Nick Schifrin contributed to this report.