Keeping things surprisingly low-key, Heidi Montag and Spencer Pratt enjoyed a casual, costume-free Halloween outing on Saturday (October 31).

The “Hills” co-star couple kicked things off with a relaxing lunch in Beverly Hills, with the twosome chatting away on an outdoor patio.

Feeling refreshed after their Halloween lunch, the MTV reality stars continued along - making their own little auto-biographical film on a handheld video camera.

Amidst their travels, Heidi and Spencer also fit in a bout of shopping - loading up with a few items before heading back to the homefront.

While her baby daughter Stella is a bit too young to take part in this year’s Halloween festivities, that didn’t stop Ellen Pompeo for enjoying the annual holiday affairs.

Spotted out on Saturday (October 31), the Meredith Grey actress was dressed in all-black as she dropped by a local Halloween party before later stopping to get a coffee at a Los Angeles cafe.

Meanwhile, you can catch Miss Pompeo this Thursday, November 5th in an all-new episode of “Grey’s Anatomy” airing titled “Invest in Love”.

Per the show’s Web site, a synopsis tells: “The parents of Arizona’s 10-year-old patient offer the hospital a generous donation, but Arizona finds herself in a conflict of interest when the patient’s condition worsens; Cristina tests her boundaries with Owen.”

Getting into the holiday spirit, Miranda Cosgrove paid a visit to the London Dungeons for Halloween on Saturday night (October 31).

Joined by her mother and a few pals, the “iCarly” cutie was all decked out in a cat costume as she enjoyed the haunted grounds.

As for her costume choice, Miss Cosgrove tweeted, “Happy Halloween!!! Turns out people do celebrate Halloween in London!”

The 16-year-old adds, “I’m gonna get a last minute costume together. I dressed up as a cat! My entire nose is black! I’m going to the London Dungeons! It’s supposed to be haunted! This Halloween is gonna rock.”

Earning a little extra cash with hosting duties, Holly Madison was in full costume as she hit up Studio 54 in the MGM Grand Resort Hotel in Las Vegas on Saturday night (October 31).

Joined by fellow beauty Laura Croft, the Playboy babe was on-hand to make sure partygoers had a night to remember as they celebrated during the Hollyween fete.

Meanwhile, Miss Madison recently spoke with the Toronto Star, during which time she joked (we hope) about eyeing a political future.

Holly declared, “I want to be the Mayor of Las Vegas. I’d be really good at it,” before saying that she wasn’t in a position to reveal her “campaign plans now.”

Enjoying their first Halloween as a married couple, Khloe Kardashian and Lamar Odom were among the stars taking part in the night’s festivities in West Hollywood on Saturday (October 31).

The E! reality star and her Lakers basketballer hubby dressed up as Batman and Catwoman for a big bash at Club XIV.

Once inside, the pair mingled with fellow guests, with the crowd on-hand including Carolin D’Amore, Simon Rex, Lisa Alvarez and the Wayans brothers.

In related news, Khloe was busy on ehr Twitter account, trying to boost interest in MTV’s Styl’D, which features her sister Kim in tonight’s episode.

She writes, “Watch @kimkardashian get dressed this Sunday night at 10pm on a hot new MTV show called Styl’D! Should be amazing! Lots of drama! LOL.”

Making for quite the sight to be seen, Gwen Stefani and Gavin Rossdale were spotted out alongside their sons, Kingston and Zuma, in Los Angeles on Saturday evening (October 31).

The foursome stepped out dressed in cute costumes (aside from Gavin) to collect a few bagfuls of goodies as they went door-to-door for the Halloween holiday trick-or-treating session.

The Halloween outing comes just one day after Gavin celebrated his 42nd birthday.

Keeping things low-key, Gwen and Gavin stepped out for a quiet lunch on Friday afternoon at popular local eatery, Madeo.

Getting into the Halloween spirit, Kate Beckinsale, Len Wiseman and daughter Lily Mo Sheen were all dressed up in Los Angeles on Saturday night (October 31).

After spending the day out shopping in Santa Monica, the happy family posed for pictures as they left their house, en route to a local Halloween party.

The outing comes as Kate readies to get promoting for her upcoming movie, “Everybody’s Fine” - which hits theaters on December 4th.

Co-starring Robert DeNiro, the film sees “a widower who realized his only connection to his family was through his wife set off on an impromptu road trip to reunite with each of his grown children.”

Always in the mood for a night of partying, Annalynne McCord was once again helping sister Rachel celebrate her 21st birthday at TABU Ultra Lounge inside the MGM Grand Resort Hotel in Las Vegas on Saturday night (October 31).

Making for Rachel’s second birthday bash in the past few days, the most recent soiree was an appropriately themed Halloween fete - with all three McCord girls decked out in their costumes.

As previously reported by Gossip Center, the McCord ladies partied it up at L.A. hot spot Sky bar at the Mondrian hotel earlier in the week.

The Tinseltown event event brought out fellow friends including Michael Steger and Eddie Griffin.

Known for her love of the Halloween holiday, Heidi Klum was back at it with another round of her annual fete at Voyeur in West Hollywood on Saturday (October 31).

For the festive affair, the Victoria’s Secret beauty and her musician hubby Seal both dressed up as crows, greeting a long list of celebrity guests for the devil’s night doings.

As for the guest list, couples turning up at Voyeur included tooth fairy lovers Paris Hilton and Doug Reinhardt, bacon and egg mates Kelly Osbourne and Luke Worrall, gangster vampires Eliza Dushku and Rick Fox, as well as the lovely Jessica Alba and her husband, Cash Warren.

Others gracing the Tinseltown hotspot for Heidi’s shindig included the stars of “90210”, Celeta, Perez Hilton, Cisco Adler and Derek Hough, among numerous others.

Having flown into town the previous day, Audrina Patridge hosted a big “I Dream of Audrina” Halloween party at Dusk Nightclub in Atlantic City on Saturday (October 31).

The MTV reality star showed off her fabulous figure in a sexy genie costume, posing for pictures and chatting with fellow partygoers during the festive soiree.

As previously reported by Gossip Center, Miss Patridge made the trip in part to talk up her forthcoming reality show, ‘The Audrina Show,’ which will hit MTV in 2010.

As of now, she’s currently been busy finishing up shooting what will be her final season on “The Hills” - which airs on Tuesdays at 10PM on MTV.