(In the same interview, Mr. Olbermann could not help commenting: “Phil thinks he’s my boss.”)

Even some of those at MSNBC who acknowledged being spurned or insulted by Mr. Olbermann said they remained in awe of his productivity and the effect he had on the network. Several considered him in essence a five-day-a-week editorial writer, who had to perform his editorial live on television.

It was an “incredible energy expenditure,” one longtime acquaintance of his said, suggesting that there was no reason to think Mr. Olbermann would stay in his chair indefinitely.

Mr. Olbermann himself alluded to the stresses of the job when he said on Friday night, “There were many occasions, particularly in the last two and a half years, where all that surrounded the show, but never the show itself, was just too much for me.”

In an interview, Mr. Griffin acknowledged that Mr. Olbermann was a “brand definer” for MSNBC  not just because of the success of “Countdown” but because his show was used to develop other hosts for the network as well.

Rachel Maddow started as a frequent “Countdown” guest, as did Lawrence O’Donnell, who began as a fill-in host for Mr. Olbermann and will inherit his 8 p.m. time slot on Monday. Mr. Griffin called Mr. Olbermann “the tent pole at the center” of the network’s sensibility.

At the same time, stories about Mr. Olbermann’s thin skin circulated widely in the newsroom. One such story, which was recalled independently by two hosts, dates to early December, when Mr. O’Donnell, then carving out some success as the 10 p.m. host on MSNBC, collegially proposed via e-mail that Mr. Olbermann come on his show to talk about President Obama’s tax-cut compromise.

Mr. O’Donnell had written this post on Twitter: “Liberal critics of the Obama deal say exactly what Pat Buchanan said of George H. W. Bush: he’s weak.” The message speculated that Mr. Obama’s critics would do to him what Mr. Buchanan “did to H.W. Bush: destroy him and help elect a president from the other party.”