15 - The number of former WWE Women's Champions who were in the Royal Rumble Match

There was a great mix of legends, veterans, and newer talent in the Royal Rumble Match. With that mix, there was an even split of 15 women who have been women's champion in the WWE and 15 women who haven't held the top women's prize in the business.
The following women have won the women's championship within the WWE: Sasha Banks, Becky Lynch, Lita, Molly Holly, Michelle McCool, Nattie, Kelly Kelly, Naomi, Jacqueline, Beth Phoenix, Mickie James, Nikki & Brie Bella, Bayley, and Trish Stratus.
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Of those who have yet to win gold in the WWE, there is a couple of women that seemed destined to do so in 2018 such as Asuka, Nia Jax, and "Miss Money In The Bank" Carmella.