Paterno's son, quarterback coach Jay Paterno, thanked the crowd on behalf of his father. He said that because of chemotherapy Paterno was a little weak so he couldn't come outside.
Joe Paterno has been diagnosed with what his family has called a treatable form of lung cancer.
"Happy birthday JoePa, Happy Birthday JoePa ... and many more," the fans serenaded several times to the tune of the traditional birthday song during their seven-minute visit. Most of the gathering, which included a few children, stayed on the sidewalk and just off the Paternos' property, about 30 feet from the front door.
Wearing rain slickers or hooded jackets, most fans gathered at a statue dedicated to Paterno outside Beaver Stadium and made the roughly 15-minute walk to Paterno's modest ranch home near the end of a dead-end street. The property is decorated with bright Christmas lights.
Fans said they began planning the visit about two weeks ago. They also delivered cards as part of a drive from a Penn State alumni group in Baltimore to send Paterno 109,000 birthday cards - a number nearly identical to the capacity of Beaver Stadium.
Jay Paterno said he didn't know how many cards the family received, but joked they would have to weigh all of them.
"It was just to wish him a happy 85th birthday, have fun, show him our support and tell him we still love him," Sue Lelko, of Port Matilda, decked out in blue Penn State sweats, said about the trip to wish Paterno well.
Fans broke out into a chorus of "We Wish You a Merry Christmas after Paterno's wife, Sue Paterno, also came out briefly while trying to get grandchildren running in the yard to return home.
"Thank you very much and have a Merry Christmas," she said.
University trustees fired Paterno last month amid mounting pressure that school leaders should have done more to stop allegations of child sex abuse against retired defensive coordinator Jerry Sandusky that spanned from 1994 to 2009.
Paterno testified before a grand jury investigating Sandusky about a 2002 allegation reported by a graduate assistant that Paterno then relayed to a superior, but prosecutors have said he is not a target of the probe. Sandusky is awaiting trial after pleading not guilty.
Paterno has called the allegations troubling and urged the public to let the legal process unfold. He initially announced his retirement Nov. 9, taking effect at the end of the season. That day, he called the scandal "one of the great sorrows of my life. With the benefit of hindsight, I wish I had done more." The trustees fired him about 12 hours later.
On Wednesday, a prominent Penn State donor, Anthony Lubrano, released a letter critical of the way Penn State leaders handled the initial week of the crisis.
Lubrano is a 1982 graduate whose name is on a state-of-the art baseball park that opened on campus in 2006. He said the letter was sent to fellow alumni.
In the letter with the subject heading of "Due Process," Lubrano said "In America, the presumption of innocence is a fundamental right. However, on the night of November 9th, a rush to judgment appeared to have occurred."
He wrote that others "outraged by the failure of the leadership of Penn State to allow for due process" sign a separate online petition. The petition contained nearly identical wording to an online letter of support signed by nearly 450 of Paterno's former players, including Heisman Trophy winner John Cappalletti, LaVar Arrington and current Raiders offensive lineman Stefen Wisniewski.
Lubrano said he coordinated with letter organizers after the former players released their statement of support Tuesday night.
"It's about celebrating Joe's birthday today. We just want to wish him well with his recovery and everything," one of the organizers, Hall of Famer and Nittany Lions standout tailback Lydell Mitchell, said Wednesday. "He's going through a stressful time right now."