Lioness Star Thad Luckinbill Played Kaley Cuoco's Boyfriend On A Hit Sitcom

Long before Thad Luckinbill stepped into the role of Kyle on "Lioness," he played Kaley Cuoco's boyfriend on a hit sitcom. We're talking about Luckenbill's role as Donny Doyle on "8 Simple Rules," which was originally titled "8 Simple Rules ... for Dating My Teenage Daughter." Donny played the romantic interest of Cuoco's character, Bridget Hennessy.

Luckinbill's first appearance on "8 Simple Rules" (one of Cuoco's best TV shows) was Season 1, Episode 26, titled "The Doyle Wedding." The episode revolves around the Hennessy family — led by Paul Hennessy (John Ritter) — attending a wedding of their neighbors, the Doyles. It also serves as the very beginning of Bridget's romantic spark with Donny. Although she first used to think Donny was a little bit of a dork, she sees him in a new light during the ep.

Luckinbill's last appearance was Season 2, Episode 3, titled "Donny Goes AWOL" — and a lot of big things happen in between. In addition to Donny returning to the Naval Academy, Bridget now has another romantic interest to juggle. She also uses a video postcard set up by Donny's family to break up with him, leading to drama. "Donny Goes AWOL" is notable most of all because it served as Ritter's last appearance before his tragic, untimely death.

Thad Luckinbill and Kaley Cuoco didn't just play sweethearts on TV — they also dated in real life. According to Us Weekly, they were romantically linked in 2002. That said, not much is known about their relationship, or the reason why it ultimately ended. There are a few press photos of the pair posing together on red carpets, and not much else.

As of 2026, both Cuoco and Luckinbill are worlds away from their early '00s romance. Luckinbill, for his part, has been married to Amelia Heinle, his "The Young and the Restless" co-star, since 2007. They have two children. And although Luckinbill initiated divorce proceedings in 2017, they've since reconciled and are enjoying marital bliss, per Hello!.

Meanwhile, Cuoco is currently in a relationship with her fiancé, actor Tom Pelphrey. In October 2026, she gave birth to their second child together. "Philomena Carmine Bobby Pelphrey ... 10/12/26," Cuoco posted to Instagram. "There are no words to describe this feeling once again. What a blessing." She continued, "We are so grateful for the crazy wild up and down journey that brought us to our little Philo. Family officially complete. Time to bring Matilda's baby home! @tommypelphrey life exploded the minute we met, and the gifts keep coming."