She was a Beverly Hills princess then became famous with her sister as they partied with Britney Spears. She next wed BIG money. Who is she?

She was raised a Beverly Hills princess with a huge mansion and a private driver.

When she was a teenager spending time in New York City and Hollywood, she shot to fame with her older sister.

They were the blonde bombshells who hit nightclubs and drank Dom Perignon. Their pals were Britney SpearsLindsay Lohan and Nicole Richie.

Later, in her 20s, she got into design and fashion in Manhattan while her sister went on to become massively famous. 

And in her 30s she got married to big, old money and went on to have kids.

She was raised a Beverly Hills princess with a huge mansion and a private driver. When she was a teenager she shot to fame with her older sister. Who is she?

She was raised a Beverly Hills princess with a huge mansion and a private driver. When she was a teenager she shot to fame with her older sister. Who is she?

These days she still looks fantastic as she works on various projects with her sister and mom, which is also famous (by the way, her aunts are famous too).

On Monday evening her older sister posted this flashback photo to celebrate her 41st birthday.

Who is she?

She is Nicky Hilton.

Her sister is Paris Hilton, her mother is Kathy Hilton and her aunts are Kyle and Kim Richards.

Paris, 43, shared her note for Nicky after the star turned 41 on Saturday.

'Twinning since Day 1. Happy Birthday to my beautiful sister @NickyHilton!' she wrote on Instagram.

'Since the beginning you have been by my side, my partner in crime, best friend, and confidant,' Paris continued. 'You’ve always been the one I look up to, and I’m endlessly proud of everything you accomplish as a wife, mother, and total boss babe ✨.'

She is Nicky Hilton, left. Her sister is Paris Hilton, right, her mother is Kathy Hilton and her aunts are Kyle and Kim Richards

She is Nicky Hilton, left. Her sister is Paris Hilton, right, her mother is Kathy Hilton and her aunts are Kyle and Kim Richards

Paris, 43, shared her note for Nicky after the star turned 41 on Saturday. 'Twinning since Day 1. Happy Birthday to my beautiful sister @NickyHilton!' she wrote on Instagram

Paris, 43, shared her note for Nicky after the star turned 41 on Saturday. 'Twinning since Day 1. Happy Birthday to my beautiful sister @NickyHilton!' she wrote on Instagram

They are seen in several photos as children, as teens and then as adults.

This comes after Nicky said she has rules with husband James Rothschild.

They have been married for 10 years. 

She spoke to People at her MyTheresa launch party and shared insight about what makes their relationship work.

The couple share daughters Lily-Grace, eight, Teddy, six, and son Chasen, two.

Hilton revealed: 'My husband and I, with our work, we travel a lot, but we will not leave the children alone. So we try and divvy up our work trips and make sure that we're always present.'

And she praised parents Kathy and Richard Hilton for showing her an 'amazing template' of a strong union.

Nicky and husband James Rothschild have been married for nearly 10 years, and now the heiress is opening about their marriage agreements; pictured in March

Nicky and husband James Rothschild have been married for nearly 10 years, and now the heiress is opening about their marriage agreements; pictured in March

Detailing what her mom has taught her, she said: 'I feel like some of the advice my mom has always given me is [to] never stop having fun, never go to bed angry and just to stop and smell the roses and enjoy every moment.'

And to maintain her bond with her husband, 39, Nicky shared: 'We always try and just make that special alone-time date night.'

On Saturday she had a double celebration as she turned 41 and also launched her collaboration with designer Rebecca Vallance. 

In addition to sister Paris and brother-in-law Carter Reum, Kris Jenner, Rachel Zoe, Jennifer Tilly, Kelly Osbourne and Dylan Mulvaney were also present.

Nicky told People magazine, 'I have been a huge fan of Rebecca's designs for many years. [I've] been wearing them. 

'Me, my mom, my sister — we all love them. So to be able to collaborate with one of my favorite designers is really a dream come true. We have such a similar aesthetic, DNA, and I think you will see that in all the pieces.'

About making their partnership work, the mom-of-three explained, 'She would fly to New York, we would meet in Europe, and we really, really worked very collaboratively on this collection.'

The duo produced a limited edition collection that 'features impeccably cut statement dresses that capture the iconic Rebecca Vallance brand codes, reimagined through Hilton’s lens,' per the official website.

Hilton revealed: 'My husband and I, with our work, we travel a lot, but we will not leave the children alone. So we try and divvy up our work trips and make sure that we're always present'

Hilton revealed: 'My husband and I, with our work, we travel a lot, but we will not leave the children alone. So we try and divvy up our work trips and make sure that we're always present'

The designs emulate 'that special holiday feel through a timeless color palette' which Nicky noted also includes some non traditional shades.

'I think with the holiday collection, people usually think jewel tones, but I really wanted to think outside the box. 

'I wanted to include some ice blues, which is my favorite color,' she remarked.

Promoting the fresh looks on Instagram over the weekend, Nicky wrote in a caption to her nearly two million followers, 'Feeling festive already- 61 days until Christmas!' 

Hilton modeling in a mansion this week

Hilton modeling in a mansion this week