Bill Paxton, the affable actor who was a co-star in a string of 1990s blockbuster movies including “Twister,” “Titanic” and “Apollo 13,” and who later played the lead in the critically acclaimed television drama “Big Love,” has died. He was 61. His death, from complications of surgery, was announced on Sunday by a family representative. The statement did not say when or where Mr. Paxton died, but