Katie Cassidy, daughter of former teen heartthrob David Cassidy, shared lessons from her father's death.

"The Partridge Family" star David Cassidy "Arrow" actress Katie, 31, was his eldest daughter, from his relationship with model Sherry Williams. Katie has a younger half-brother Beau from David's third marriage.

Katie followed in her father's footsteps into acting, becoming a regular in The CW's Arrowverse as Laurel Lance/Black Canary/Black Siren. She took to social media to share her father's bittersweet and heartbreaking final words:

Wow. So much wasted time. David Cassidy had his struggles in life -- from alcoholism to dementia and three marriages ending in divorce. But how sad for a man so famous and beloved for decades to wish on his deathbed that he had spent his time differently.

In lighter news, The CW's superhero crossover starts tonight, with "Supergirl," followed by "Arrow."

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