Cannell dealt with dyslexia through school but overcame it to write literally hundreds of television episodes and 17 thriller novels. Shows he produced would end with a scene of Cannell writing, finishing a script with a flourish as he plucked the page from the typewriter and flipped it into the air, where it faded into the logo of his company -- a stylized "C" made by pages curling up from a ream of paper.
His influence on television ran from selling a story idea to Mission: Impossible in 1966 to helping shepherd the careers of people like The Sopranos creator David Chase. Even though he created absolute gems like Rockford, he could also throw some serious schlock on the screen, like Riptide and the Lorenzo Lamas vehicle Renegade (in which he also acted), but such is television. Cannell had a shelf of awards, but I suspect that were he to have been asked, he might tag his 46-year marriage, three children and three grandchildren as one of his prouder achievements (a fourth child preceded him in death).