From the NYTimes obituary:
For 30 years, beginning in the early 1970s and extending through the 1990s, television viewers could hardly go a week without running into a show written by Mr. Cannell. His writing credits include more than 1,000 episodes of various series, primarily crime dramas, and he is listed as the creator of almost 20 series — some long-running hits like “The Rockford Files,” and “The Commish,” others quick flame-outs like “Booker. ” At one point in 1989, Mr. Cannell’s company was producing five series on three networks. One of them, “21 Jump Street,” introduced a future Oscar nominee to public acclaim: Johnny Depp.
But that was not unusual. Mr. Cannell’s shows often opened doors for emerging actors. Jeff Goldblum gained his first wide notice in a short-lived but well-remembered Cannell series, “Tenspeed and Brown Shoe.” And “Wiseguy” gave another future Oscar winner, Kevin Spacey, a chance to stand out in a memorable extended turn as a villain.
"The Rockford Files" was certainly my favorite of Cannell's work, although that owes at least as much to my lifelong admiration for the wry and unflappable James Garner (who I almost but not quite got to meet at the catfish diner in my home town before bypass surgery made him clean up his dietary act). "The A-Team" might be one of Cannell's most commercially successful series, but I always had a special fondness for the canceled-too-soon Stingray, which was into inexplicable music videos replacing plot movement a couple of years before Miami Vice:
Mr. Cannell suffered from extreme dyslexia, which went undiagnosed and all but ruined his school years. Despite inheriting his family’s intense work ethic, he failed three grades and was unable to retain a football scholarship to the University of Oregon because of his academic record.
But a professor there recognized his writing gifts and encouraged him.