Carnival spokesman Robert Slight told how they had contacted a number of celebrities - including Britney Spears, Rod Stewart and Jessie J - but most replied back to say they were not available.

BBC: Beyonce

Other women on our list, including Rhianna, Britney Spears and Katy Perry, also ranked in the top tier of social influencers.

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Conway is leading the Causes.com campaign along with other big names including Ryan Seacrest, Jack Dorsey, Britney Spears, MC Hammer, Suze Orman and Tyler Florence.

CNN: Websites go dark for Sandy Hook moment of silence