The Doctor's Constant Companion

"The Doctor is a legend woven throughout history. When disaster comes, he's there. He brings the storm in his wake and he has one constant companion," Clive said to Rose, brandishing the sketch. "Who's that?" Rose asked, frowning. "Death," Clive said dramatically, and Rose gulped. "My name is Thantos," I said, tightening my grip on my scythe, "and I am Death."