Steve McQueen!

From this movie till they worked again in the Towering Inferno - Steve held a very competitive grudge against Newman.

When The Towering Inferno came around Steve had a enough star power to ask for top billing - Newman and he had to work out the billing order by having Newman's name higher but Steve's name first. They were supposed to work together in Butch Cassidy and the Sundance Kid but they could never work out the billing order at that time