As "The Big Bang Theory" approaches its May 16 series finale, Kaley Cuoco is taking time to thank a fan who has inspired her all season long.

"My sensational friend Isaiah… has sat in the front row of our audience for the entire run of season 12. He suffers from (epidermolysis bullosa), yet when I look into the crowd, he always has the biggest smile on his face," Cuoco wrote in an Instagram post Thursday.

The actress shared a collection of on-set photos she'd taken with Isaiah Zarate, who has a rare "disabling and life-threatening" skin disease, according to the official website for the Epidermolysis Bullosa Medical Research Foundation.

"He has become quite a key player here at ("Big Bang Theory") and I couldn’t love him more," she continued. "Isaiah, thank you for always reminding me how a smile can change an entire day. You are an inspiration and I will fight with you to find a cure!!"

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