There's a certain kind of pang you feel when a beloved person from your childhood passes away, and that's exactly how so many millennial and Gen X moms are feeling right now. Emilio Delgado, who played Luis Rodriguez on Sesame Street for 45 years, has died at the age of 81.

Delgado passed away at his New York City home on Thursday surrounded by his wife and children, according to PEOPLE. He was diagnosed with Multiple myeloma, a blood cancer, over a year ago.

"Sesame Workshop mourns the passing of Emilio Delgado, known the world over for his role as Luis on Sesame Street," reads the caption to a photo of Delgado on the official Sesame Street Instagram account. "A beloved member of the Sesame family for over 50 years, his warmth and humor invited children to share a friendship that has echoed through generations."

According to Sesame Workshop, Delgado was incredibly proud to hold the record for the "longest-running role for a Mexican-American in a TV series."

He joined the cast of Sesame Street in 1971, and remained on the show with other beloved characters Maria, Gordon, and Bob until 2016. He and the other original cast members returned for the show's 50th anniversary special in 2019.

In addition to his work on the most famous children's program of all time, PEOPLE reports he spent many years fighting for racial and social justice as a Chicano rights activist. He was also part of the United Farm Workers led by César Chávez, and he participated in protests against the Vietnam War, according to the Bayard Rustin Center for Social Justice, for which he served on the Board of Directors.

Sesame Street's favorite couple, Luis and Maria (played by Sonia Manzano), were such a warm demonstration of what love looks like to so many kids for so many years. The relationship between their characters even played out on-screen, culminating in a wedding episode—which was basically revolutionary at the time.

“Since kids see love in terms of physical things like kissing, hugging, giving flowers, we showed Maria and Luis doing a lot of that,” Manzano, who also wrote for the show, told The New York Times in 1988.

I was an only child for almost seven years and my parents were fairly hands-off, emotionally speaking. This meant I spent a lot of time in front of the television, immersing myself in fictional families and other worlds that made me feel like I belonged and that I was safe and loved. Luis and Maria were a huge part of those feelings for me, and even now, all these years later, I still get choked up thinking about how much I loved them.

I can only assume many, many other children felt the same way thanks to the brilliant work of Emilio Delgado and Sonia Manzano. Watching older episodes of Sesame Street with my own children is a true gift for those reasons and more.

In 2019, former New York City mayor Bill de Blasio declared Oct. 15 "Emilio Delgado Day" during a Hispanic heritage celebration.

“At a time when, if you saw diversity on television, it often was with stereotypes, and not the good kind of stereotypes,” Mr. de Blasio said at the time. “Emilio was one of the people who broke the mold, created a positive role model, for everyone, but particularly for children who didn’t get to see or hear people who looked like them and spoke like them.”