These A-list actors started in horror movies, sometimes very low budget, but went on to mainstream success.
Jamie Lee Curtis is a prime example, starring as Laurie Strode in the original 1978 Halloween and reprising the role in many sequels, including the recent reboot trilogy. She also made two small cameos in Halloween 3: The Season of the Witch.
Curtis appeared in many other hits, including Trading Places, A Fish Called Wanda and True Lies, before winning an Oscar for Everything Everywhere All at Once. She also appeared in Halloween Ends.
Basically the gold standard of stars who turned horror careers into just plain thriving movie careers
Author's summary: A-list actors started in horror movies and achieved mainstream success.