Unlike some A-list TV producers, the unifying elements characterizing John Wells’ series aren’t always readily apparent. Yes, they tend to feature large ensembles, but the milieu is forever changing — from doctors to cops, extended (and dysfunctional) families to the White House.

Look closer, though, and there are recurring attributes and themes: Weaving together ambitious plots and complicated characters. Tackling the sort of social issues that can make network execs squirm. No certainty of happy endings. And a willingness to take risks and, occasionally, fail.

Wells’ contribution to television, however, goes beyond that — exhibiting a rare combination of creative chops and managerial skill. The former trait has allowed Wells to produce Emmy-winning series such as “ER” — which by virtue of its success, helped define the serialized drama of the 1990s — and “The West Wing.” The latter has enabled him to juggle as many as three or four programs at a time, while dabbling in features and twice heading the Writers Guild of America.

During his first WGA West stint from 1999-2001, a guild colleague who worked alongside Wells through contract negotiations with the studios once marveled at his ability to compartmentalize, singularly focusing on a task or problem before moving to the next item on his to-do list. That would seem to explain how Wells has kept piling so much on his plate — the ultimate hyphenate in terms of writing, producing and directing, in addition to creating climates as a showrunner where other writers can flourish.

Still, emphasizing the more pragmatic aspects of Wells’ career can easily overshadow the way he has gravitated toward quality material and continued to take chances — even if a series such as “Southland,” the gritty police drama launched by NBC before finding renewed life on TNT, is by no means a mass-appeal hit.

As for his extracurricular activities, it’s telling Wells has chosen to invest the time championing the professional cause of writers despite having achieved the sort of personal success that makes the impact on his own financial status at best incremental. Perhaps that’s because he identifies primarily with that discipline, despite his diversified portfolio.

“Any time somebody says to me, ‘What do you do?’ I always say, ‘I’m a writer,’?” Wells said in an interview during his first guild stint. “I don’t even hesitate about it.”

Creatively speaking, perhaps the signature qualities to Wells’ TV resume are attention to detail and advocacy on behalf of the audience. The latter trait has inspired him to lament, for example, the rising amount of commercial time in broadcast dramas — losing roughly five minutes of content to advertising and promotion since “ER” premiered — because it dilutes storytelling, and thus the viewer’s experience.

In this regard, an anecdote from “ER’s” run is enlightening. When George Clooney made a surprise return — reuniting his character with that played by Julianna Margulies in her swan-song episode — Wells went to extraordinary lengths to protect the twist, promising the crew bonuses if the secret held, and storing the footage in his refrigerator until the night before air.

Its success and longevity notwithstanding, “ER” arguably isn’t the best show with which Wells has been associated, but it’s the most appropriate hallmark of it: TV drama, crafted with a surgeon’s care.

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