Chad Michael Murray Surprises Teenage Cancer Survivor In Emotional Video

A teenage girl who kicked cancer's ass 3 times got the surprise of a lifetime when Chad Michael Murray showed up unannounced during an interview she was giving ... and the meeting was super emotional.

Alex, who beat 3 different types of cancer by the time she turned 18, was flown out to Los Angeles right before Christmas to appear on the "Just Between Us" podcast with Bailee Madison and Kaitlin Vilasuso for an episode on real-life superheroes ... and Bailee surprised her guest by arranging for Chad to come through.

Alex had shared in the past that watching "One Tree Hill" helped her get through chemo, so Bailee recruited Chad to make his surprise appearance.

Check out the clip ... Alex is equal parts shocked and thrilled when Chad walks into the room. There are hugs, screams and lots of happy tears.