Treat Williams made an impact when he was in front of the camera, as viewers of his favorite shows know.

Behind the scenes, the late actor greatly impacted his co-stars.

In the aftermath of his shocking death at 71 from a tragic motorcycle accident, his onetime co-stars are speaking out.

"This is a tough one, and I don't like doing this on social media, but I want to share what an absolute treasure Treat Williams was- both as an actor and a person," White Collar's Matt Bomer wrote on Instagram.

!I was so honored that he agreed to play my father on White Collar, and he jumped in and made every day on set a joy."

"He taught me in the most beautiful way- through patient example. He's one of the few actors I've worked with who always checked in on me - even years after we worked together."

"Treat- you were an amazing actor and an even better person and I will miss you," Bomer added. 

"I count myself so blessed to have known you. My heart goes out to your wife and children. Rest in Peace my friend."

Emily VanCamp, who worked with the beloved actor on Everwood and Beyond the Blackboard, took to Instagram to pay her respects to her former co-star.

"The many times we worked together- always wonderful and I was always excited for the next time," the Revenge alum shared.

"Sending all my love to your family Treat. Fly high my friend."

Fellow Everwood alum Gregory Smith shared a statement with People.

“Treat was a wonderful man and a brilliant actor. Above all, he loved his family so much. I’m very grateful for the time I got to spend as part of his extended tv family," the actor shared.

"He made an indelible impression on me during my most formative years."

"I will always cherish my time with Treat and think fondly of his stories, his laugh and his passion for adventure. I’m sending love to his family, Pam, Gil and Elinor. He will be deeply missed.”

Wendell Pierce, who starred opposite Treat on Confirmation, shared a tribute.

"Treat Williams was a passionate, adventurous, creative man," he wrote.

"In a short period of time, he quickly befriended me & his adventurous spirit was infectious."

"We worked on just 1 film together but occasionally connected over the years. Kind and generous with advice and support. RIP," the Suits alum added.

Warren Leight, who worked as a showrunner on Law & Order: SVU, also shared a tribute.

"I knew Treat for a long time. One of the nicest guys I've ever worked with. A beautiful actor and person," he wrote on Twitter.

"His SVU episode, Spiraling Down, was among the most memorable performances in my entire time there. I'm shocked, and heartbroken. Godspeed, Treat."

Treat's agent, Barry McPherson, shared the news of the Chesapeake Shores alum's passing in a statement to People on Monday evening.

He was killed this afternoon. He was making a left or a right [and] a car cut him off. I'm just devastated. He was the nicest guy. He was so talented."

"He was really proud of his performance this year. He's been so happy with the work that I got him. He's had a balanced career."

We extend our thoughts and prayers to Treat's loved ones during this difficult time.

May he rest in peace.

Paul Dailly was an Associate Editor for TV Fanatic.Follow him on X.