For a while now the 'hottest' celebrity/beauty collaborations have been reality TV stars flogging their beauty wares. But thanks to a host of A-listers these collaborations have regained their superstar status.

It all started last year when Katie Holmes signed on to Bobbi Brown as the make-up artist's first ever celebrity face. It was revealed that Holmes would actively work with Brown on the collaborations going forward. This weekend Holmes ramped up her involvement in the beauty industry by signing on the dotted line for yet another beauty brand – this time to luxury haircare brand Alterna as co-owner, as well as spokesperson (its Caviar shampoo and conditioner is a favourite with the actress).

Four months ago another actress signed up in the same role for another haircare brand. In October it was announced that Jennifer Aniston had started working with Living Proof as co–owner and spokesperson saying, 'What caught my attention about Living Proof is the company’s unique approach to hair care – using scientific technologies to offer women actual proof in a bottle rather than hoping for results. After using these products, I felt like I finally discovered a solution that works every day.'

But while Aniston's hair may be her crowning glory, she's also just been signed to Aveeno for a rumoured $10 million as the face of the skincare brand.

It doesn't stop there. Last week Drew Barrymore, who was until recently the face of all-American beauty brand Cover Girl, launched her make-up line – called Flower – to US press. The range goes into Walmart stores at the end of January and Barrymore has already pointed out her qualifications to run a beauty brand: 'I've been in a makeup chair since I was 6.'

And that's what's at the heart of this trend. They're not just models, they're experts themselves. They work with the industry's best hair stylists, make-up artists and dermatologists and gradually soak up their knowledge. Add to that that the buying public want the hair/skin/style of their favourite celebrities – and you've got the perfect recipe for commercial success.

It would be little surprise to see a skincare line from Scarlett Johansson, who revealed in this month's ELLE magazine that had she not been an actress she would have been a dermatologist…

But we want to know - what would be your perfect celebrity/beauty brand collaboration?