It's a Celebrity B-Day Bonanza!

Better late than never! The heiress, who turned 29 on Feb. 17, finds herself the center of a Sin City bash Saturday night at TAO nightclub in The Venetian. Hilton, who partied alongside beau Doug Reinhardt and mom Kathy (not pictured), capped off the evening by blowing out the candles on a sweet rose-adorned cake.

Looks like she’s having “tutu” much fun! Jennifer Love Hewitt celebrates her 31st birthday with a costume party with pals Sunday in Beverly Hills.

Look who’s celebrating her super-sweet 16! New Moon‘s Dakota Fanning gets a jump-start on her birthday Saturday with little sister Elle by her side. The young star and 40 of her closest family and friends, including girls from her high school cheerleading squad, noshed at Beverly Hills eatery Villa Blanca.

Sure, little sis Hilary shared some big news over the weekend, but Haylie Duff has plenty to celebrate, too – her 25th birthday! All eyes are on Haylie Saturday night as she celebrates her day with pals at the Hard Rock Hotel amp Casino’s Vanity Nightclub in Las Vegas.

Talk about a strip tease! For her 22nd birthday celebration on Saturday, SportsByBrooks captured the pop star getting a birthday lap dance from a female little person at a bash thrown by her pal, Los Angeles Dodger Matt Kemp, in Phoenix. Says a source, “[Rihanna] thought it was funny!”

It may not be Simpson‘s birthday just yet (it’s in July), but the star is ready to go all out for one VIP guy in her life: Papa Joe! With an inscribed golf ball that reads “Happy Birthday Dad” in hand, Simpson heads to L.A.’s Boa Steakhouse Friday to help her pop ring in his 52nd birthday.

It’s Posh‘s littlest Transformer! Cruz Beckham turns 5 with a festive bash in North Hollywood, Calif., on Saturday. But the party began two days earlier when Cruz, his brothers (not pictured) and a gang of pint-sized revelers gathered for a swashbuckling good time at the Pirate’s Dinner Adventure show in Buena Park, Calif.