Zachary Levi has asked fans to pray for his father, Darrell Pugh.
In December, the Shazam! star revealed that his dad had undergone a five-hour surgery to treat thyroid cancer.
However, Zachary returned to Twitter on Monday to share that Darrell's condition was deteriorating.
"Sittin in my dad's hospital room with him. He's not doin so hot right now (sic). The thyroid cancer just won't quit, and is slowly overtaking his trachea. Doctor's may have a trick or two still up their sleeves to offer him a bit more time, but Papa D is not long for this world," he wrote. "But for anyone out there that feels like rollin up some spiritual sleeves and prayin, send some up for my pops. Pray that he be as comfy and at peace as a man could get. And that he head home with no fear or regrets, knowing how loved he is."
One follower also asked Zachary whether there was anything they could do to help. In response, the actor insisted he was "just fine" and was focused on supporting his dad.
"Death does not sadden or frighten me. It's actually an incredibly powerful part of life. One that we'll all reach one day. Where we get to go back to God, the source, and be surrounded by the highest vibration of energy, love," the 42-year-old added.