Throughout his life, the late actor traveled across the war-torn Middle East with the United Service Organizations, entertaining American troops stationed in Afghanistan, Baghdad and Kuwait.
Secretary of Defense Chuck Hagel honored Williams on behalf of the Department of Defense on Monday, remembering his patriotism.
"Robin was a gifted actor and comedian, but he was also a true friend and supporter of our troops," he said in a statement. "From entertaining thousands of service men and women in war zones, to his philanthropy that helped veterans struggling with hidden wounds of war, he was a loyal and compassionate advocate for all who serve this nation in uniform.
"He will be dearly missed by the men and women of the DoD – so many of whom were personally touched by his humor and generosity."
Paula Bronstein / Getty
The Oscar- and Emmy-winning star fought alcohol and drug addiction for years, and his rep said he was severely depressed leading up to his death. But for the soldiers he visited, Williams was full of pure joy.
"The entire USO family is saddened by the news of Robin Williams's passing," the USO posted Monday on Facebook. "One of the greatest comedic actors of his generation, Williams traveled around the world to lift the spirits of our troops and their families. He will always be a part of our USO family and will be sorely missed."
Sgt. Dan Purcell / U.S. Army / DOD / AP
"Robin Williams was an airman, a doctor, a genie, a nanny, a president, a professor, a bangarang Peter Pan, and everything in between. But he was one of a kind," the Commander in Chief said in a statement. "He arrived in our lives as an alien – but he ended up touching every element of the human spirit. He made us laugh. He made us cry. He gave his immeasurable talent freely and generously to those who needed it most – from our troops stationed abroad to the marginalized on our own streets."
Behrouz Mehri / AFP / Getty
"I come here for you, because I believe you're amazing," he told the troops. "It's good to be in a room with fake beer. Having just gotten out of rehab, that's a good choice, because I was violating my standards quicker than I could lower them, but –"
As his bit was interrupted by the retreat ceremony and lowering of the American flag, Williams took off his hat and bowed his head.
"I'm not gonna forget that!" he joked as the crowd roared. "I've never had an entire audience just go, 'Forget you! You have no idea!' I was also wondering, what's coming from that way, that an entire group of military people turns that way."
Watch the video of his Kuwait USO tour below:
For more on Robin Williams's tragic death and his legacy of comic genius, pick up the latest issue of PEOPLE, on newsstands Friday
The Williams family is asking well-wishers to send contributions to charities close to the actor's heart in lieu of flowers. Suggested organizations include St. Jude's Research Hospital, Challenged Athletes, USO, the Mohammed Ali Parkinson Center, the Christopher and Dana Reeve Foundation and Glide Memorial Church in San Francisco.
The Williams family is asking well-wishers to send contributions to charities close to the actor's heart in lieu of flowers. Suggested organizations include St. Jude Children's Research Hospital, Challenged Athletes, USO, the Muhammad Ali Parkinson Center, the Christopher and Dana Reeve Foundation and Glide Memorial Church in San Francisco.