John Mayer Among Friends to Remember Bob Saget on What Would Have Been His 66th Birthday

Matt Winkelmeyer/Getty Images Bob Saget and John Mayer

Today is a bittersweet one for those closest to Bob Saget.

On the day the beloved comedian would have turned 66 years old, his friends and family are paying tribute to his life and work.

"Happy Birthday, Bob," John Mayer wrote on Instagram to the late Full House star, who died unexpectedly on Jan. 9 (an autopsy later revealed he had died from head trauma consistent with some kind of fall).

Mayer continued, "We all miss you terribly down here. Though the days without you keep growing, so too does our grasp on everything we adore and admire about you, the love we learned to share because of your example, and the endless joy you gave at all times to the world around you."

He added, "I just wish so badly we were getting dinner tonight. I love you so much."

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Saget's widow Kelly Rizzo replied to the post: "Love you John. And boy did he love you. And he'd love nothing more than dinner with you tonight and you two would be lost in deep conversation while I am just entertained by you both… and then we all order a big [sundae] or a plate of cookies while we make our next dinner plans. You'd always joke that you were the 3rd wheel but then I'd say I always felt like the 3rd wheel on Bob's dinner date with you ;)"

John Stamos sent love to his late Full House costar and onscreen brother-in-law, sharing a smiling photo of him and Saget by the beach for the occasion.

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He quoted legendary actor Jack Lemmon at the top of the Instagram caption, writing, "Death ends a life, not a relationship." He continued, "Happy Birthday Bobby. I miss you madly."

Stamos' wife Caitlin McHugh Stamos also shared a photo of herself, Stamos and Saget on her Instagram Story on Tuesday, writing, "Happy Birthday Bob ❤️"

Caitlin McHugh Stamos/Instagram

RELATED: Caitlin McHugh Stamos Shares How Friend Bob Saget Inspired Her: 'He Was Always Helping People'

Saget's onscreen daughter Candace Cameron Bure also shared a bittersweet tribute on Instagram: ""I miss you 💔. Do I still say happy birthday? I don't know how this works, but I'm celebrating you today however badly my heart hurts ❤️🧡💛🥳"

Earlier Tuesday, Rizzo shared a lengthy note to her late husband that read, in part, "I pray he can see all of the love he's already getting from around the world today. Honey, everyone loves you so damn much. Everyone wants you to know how important and special you are on your special day, and we ALL celebrate you. You are one of a kind and you certainly made my world go 'round."

Rizzo, 42, closed on a personal note: "I love you more than anything and miss you every minute. Your girls and I will hold on tight to each other today. And I know you'd want me to get a martini tonight, so I'll oblige. Happy birthday, honey."

RELATED: Kelly Rizzo Says Bob Saget Is 'Still My Husband' After Death: 'The Relationship Is Different Now'

Last week, Rizzo discussed how she has preserved his memory in the four months since his death.

"It's like, he's still my husband," she told Amanda Kloots, 40, who also lost her husband Nick Cordero suddenly when the actor died of COVID complications in 2020. "It's not like, 'Oh, he's my former husband.' It's like ... the relationship is different now. It's just — it is what it is."

Leon Bennett/WireImage Bob Saget with Kelly Rizzo, Aubrey Saget and Lara Saget

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Rizzo has since moved to a new home — but she keeps reminders of Saget wherever she can. "I mean, I still talk to him and I have his pictures everywhere," she said.

Rizzo added that her relationship with Saget's daughters has been important as she has moved through her grief in the last few months.

"I know Bob would want me to be there for his girls," she told Kloots during the panel discussion. "I'm not as focused on my own grief when I'm trying to help them or support them or be there for them. When I'm doing little things to try to make them happy, it kind of takes me out of my head. And I'm also at the same time being like, 'Oh, this would make Bob so happy, just knowing that I'm trying to make them happy.'"