Donald Trump promised to put his star power on display at the Republican National Convention, but his slate of glitzy guests has lost its lustre after several big names dropped out ahead of the event.

Actor and producer Scott Baio, Duck Dynasty reality star Willie Robertson, actor and model Antonio Sabato Jr., and former "Real World" star turned congressman Sean Duffy took the podium on behalf of the bombastic business mogul Monday. Soap opera actress Kimberlin Brown and LPGA golfer Natalie Gulbis are expected to speak on Tuesday.

Absentee A-listers previously floated by Trump’s campaign have included NFL quarterbacks Tom Brady and Tim Tebow, Mike Tyson and Bobby Knight. Tebow has said he never planned to participate. Knight will reportedly address the convention by video.

At the convention, Baio described Trump as a selfless defender of American values at a time when the country is “being attacked every single day.” The actor known best for his role as “Chachi” on the sitcom Happy Days slammed Democratic nominee Hillary Clinton’s motivations for seeking the presidency, calling her “entitled.”

Duck Dynasty’s Robertson struck a softer tone, joking that he and Trump have a lot in common: hit television shows and “intelligent wives who are much better looking than we are.” He suggested Trump’s critics are out of touch with Middle America and “don’t hang out with regular folks like us who like to hunt and pray and actually work for a living.”

Here’s a look at some of the other celebrities who have thrown their weight behind the Trump campaign so far.

Jon Voight

The Oscar, Emmy, and Golden Globe-winning actor called Trump “the answer to our problems” in a statement to the right-leaning U.S. news outlet Breitbart in March.

“Donald is funny, playful, and colorful, but most of all, he is honest. When he decided to run for president, I know he did it with a true conviction to bring this country back to prosperity. He is the only one who can do it. No frills, no fuss, only candid truths,” he said.

Aaron Carter

The former child pop star endorsed Trump via Twitter, sparking a backlash from some of his fans. Carter held his ground, but later clarified that he doesn’t support all of Trump’s policies.

Kid Rock

Trump’s business savvy style impressed Kid Rock, according to an interview with Rolling Stone. "Let the motherf------ business guy run it like a f------ business,” he told the magazine. “His campaign has been entertaining as s---."

Jesse James

James took to Facebook to with a lengthy post about his former “Celebrity Apprentice” boss.

“I was able to observe him and his kids in their day to day routine. What I saw was a person that treated everyone with respect. Even the (Hispanic) guys in the mail room. He had coffee from the coffee machine and BS'd with them every single morning. Trash men and cops would stop him on the street and he would stop whatever he was doing and spend a little bit of time with every one of them,” James said of his 2009 stint on the NBC reality show.

Mike Tyson

Tyson and Trump became friends as the former heavyweight champion fought some of the biggest fights of his career at the real estate mogul’s hotel-casinos. Tyson, who converted to Islam while in prison, says he supports Trump’s bid for the U.S. presidency in spite of his controversial remarks about Muslims.

Stephen Baldwin

The youngest Baldwin brother has been fired twice on “The Celebrity Apprentice,” but he hasn’t let that get in the way of his admiration of his former reality show boss’s appeal as a political outsider.

"I think he's fantastic. I love him. I think he'd make a great president,” said Baldwin in a July 2015 interview with CNN. “He's not a politician, and he doesn't care what anybody thinks. And that's why he's surging in the polls.

Dennis Rodman

Trump praised the NBA hall-of-famer for his visit to North Korea in 2013 where he met and befriended leader Kim Jong-un. Rodman tweeted his support for Trump in July 2015. He has also appeared on “The Celebrity Apprentice.”

Gary Busey

Gary Busey and Donald Trump share more than their messy mops of blond hair. The actor and contestant on “The Celebrity Apprentice” endorsed Trump for president in 2011, and has expressed support for his latest campaign.

"He's a great guy. He's sharp. He's fast," he told Fox411. "He can change the country after the last eight years."

Hulk Hogan

Hulk Hogan told TMZ last August that he wants to “Make America great again” by joining Trump as his running mate.

Terrell Owens

Owens called Trump “a guy who won't put up with B.S. and has what it takes to change how government is run,” in an interview with TMZ Sports. He also recently appeared on "The Celebrity Apprentice."

Jesse Ventura

The former Minnesota governor and pro wrestler doesn’t claim to support either U.S. political party, but said that he hopes Trump wins on his YouTube show.

Ivana Trump

The ex-wife of the presumptive Republican nominee gave her endorsement at a posh luncheon with her socialite friends in October 2015.

Ted Nugent

The gun-loving musician said Trump "should be given the Medal of Freedom for speaking his mind in such a bold, honest, and straightforward manner,” in an article he wrote for WorldNetDaily.

Wayne Newton

The long-time Las Vegas entertainer threw his support behind trump in an October 2015 appearance on Fox and Friends.