From poll-watching to vid-making to anthem-writing, Hollywood has been busy in the election’s final week.

In the final days before the most expensive and one of the most caustic elections in political history, one of the more popular Web videos comes from Joss Whedon, who “endorses” Mitt Romney because he thinks it will put the country “on the path to the zombie apocalypse.”

With more than 5 million YouTube hits since it was introduced on Oct. 28, the video is biting, satirical and perhaps the first major play for the ComicCon vote.

It also illustrates Hollywood’s influence in this election cycle, and how many in the biz are still fighting the fight.

Brad Pitt has pledged $100,000 to support same-sex marriage in ballot campaigns in four states, while Robert Redford recently sent out a fundraising appeal for support of Democrat Richard Carmona, the former Surgeon General who is running for Senate in Arizona . Answering a call from the Obama campaign, DreamWorks topper Stacey Snider served as a poll-watcher of early voting in Nevada.

In the election’s remaining days, a number of entertainment figures will be out on the trail, making phone calls or volunteering . Jon Voight is traveling with the Romney campaign, while a host of celebrity supporters were queueing up for Obama over the weekend. Jack Black and Ryan Adams led get-out-the-vote efforts for Obama last week in Ohio and Colorado, respectively. Bruce Springsteen will travel with the prez in the campaign’s final day, Nov. 5, and play at three stops: in Madison, Wis.; Columbus, Ohio; and Des Moines, Iowa.Actually, given how much has been made of the “enthusiasm gap” among showbiz’s Obama supporters this time around, as well as whether candidates would be wise to embrace the industry’s elite during tough economic times, Hollywood has played a surprisingly larger role in this campaign than seemed likely from the start — which now feels like eons ago. Instead of treating showbiz supporters with at least some trepidation, both Democratic and Republican campaigns have embraced them.

Some examples:

According to the Center for Responsive Politics, Obama had collected $6 million from movie, TV and music donors as of the end of September . In 2008, his campaign took in a total of $9.2 million from such donors . But the 2012 figure doesn’t include money raised by outside groups that are proObama. Among these , Jeffrey Katzenberg chipped in $3 million, Steven Spielberg gave more than $1 million and Morgan Freeman wrote a check for $1 million. The chance to rub elbows with celebrities provided and even bigger impact : A May fundraiser at George Clooney’s home raised almost $15 million for the prez , the majority coming from an online contest in which smalldollar donors could enter to win tickets to the event. The Obama campaign repeated such contest fundraisers with Sarah Jessica Parker and National Basketball Assn. players, while the Romney campaign offered dinner with the candidate and Donald Trump . Down-ballot candidates also used celeb tie-ins.

In April, the proRomney SuperPAC American Crossroads put out a Web video, “Cool,” that targeted Obama as a “celebrity president,” featuring shots of him slow-jamming the news on “Late Night With Jimmy Fallon” and dancing with Ellen DeGeneres. Last month, the same SuperPAC decided it would rather join Hollywood than fight it , and put out a spot featuring Clint Eastwood, whose primetime slot at the Republican National Convention may have been ridiculed elsewhere, but earned cheers in the convention hall.

The uplifting message from 2008 has given way to dire scenarios if the other guy wins. That was true of the Eastwood ad spot, as he predicted that the country “couldn’t survive” another Obama term. But it also is true of a MoveOn spot, in which Scarlett Johansson, Eva Longoria and Kerry Washington auger what will happen to women’s health if Romney and Republicans are elected. “If you think that this election won’t affect you and your life, think again,” Johansson says. The tone also is reflected in Web videos, not just from Whedon, but in get-out-the-vote efforts in which Sarah Silverman and Samuel L. Jackson use profanity to call attention to what is at stake in the race.

That’s a far cry from 2008, when we saw Ron Howard gathering Henry Winkler and Andy Griffith for a pro-Obama video, and Will.i.am leading the viral phenomenon, “Yes, We Can.” In fact, many this cycle have voiced the feeling that they are burned out by politics.

As the race enters its final stretch, some in entertainment are making last-ditch efforts to improve the discourse, with hopes of creating some uplift amid the oppositional campaigning. Last week, Ne Yo, Johnny Rzeznik, Herbie Hancock, Delta Rae and Natasha Bedingfield released a Web musicvideo, “Forward,” capitalizing on Obama’s campaign slogan, but made outside of the campaign structure. The song was written by Gregg Alexander and Danielle Brisebois, as well as Fred Goldring, who was executive producer behind “Yes, We Can.”

Goldring says he was initially reluctant to come up with another grassroots effort, in part because he was turned off by the negativity this season. “It was all about money and how much can you raise to help counteract ads (from the other side),” he says.

But Goldring adds that his relative noninvolvement was making him feel a bit guilty. “I wasn’t as active this time. But I thought that we needed something, a bit of a spark going into the end of the election.”

There had been a lack of inspirational messages, he says, and the group aimed to deliver one. They eventually got the talent together, working for eight days on the video at a cost of less than $40,000, roughly the price of a single ticket to a high-dollar presidential fundraiser. Introduced last week, the musicvid had collected about 700,000 views in its initial few days. Goldring hopes it will be “an anthem to bring people together,” and leave supporters with a positive feeling as all the electioneering comes to an end.

Certainly the initial feeling of many in Hollywood at the finish of this election cycle is more likely to be one of relief.