Is it possible to write a truly great TV comedy that doesn’t feature at least one lovable dummy? Sure, maybe—but why would you want to?

The innocent, happy-go-lucky idiot is a character type as old as time—and it has a particularly long lineage in TV sitcoms, from the black-and-white series of yore to newer series like BoJack Horseman, which returned to Netflix Friday. Like many of these beloved dimwits, Todd Chavez—BoJack’s designated dummy—serves not only as comic relief, but also as the earnest heart of the series. Without Todd, BoJack would be a drag—but Todd, like so many of television’s lovable idiots, gives his show an irresistible sweetness, acting as a counterbalance to its darker, sharper edges. As pitch-black dramas and sad-coms seem to make up more and more of the TV landscape, these characters and their tomfoolery—or, in BoJack’s case, Todd-foolery—are even more valuable.

It’s hard to overstate the importance of someone as pure as Todd in a series that centers on the callousness of Hollywood—and, indeed, almost everyone closest to Todd is exploiting his naïveté for their own purposes. This is a guy who once embarked on a mission to rescue a chicken he’d just met and named “Becca,” not realizing she was simply squawking. This is a guy who opened a Halloween store that’s only open in January, to take advantage of what he saw as an “untapped market.” And yet, somehow, Todd always seems to do O.K. for himself; this season, he even manages to stumble into a job as an ad executive. That optimism and uncanny ability to rise above anything are irreplaceable ingredients—not just in BoJack, but in many other series as well.

Dumb side characters don’t necessarily have to play the foil; sometimes their presence simply accentuates the ineptitude of the people around them. See, for instance, Will Humphries on the BBC comedy W1A, the dumbest person of all on a show about dimwitted media types. He somehow manages to muck up even the simplest tasks, like placing invitations in the correct pre-addressed envelopes, or writing down timestamps every time Jeremy Clarkson says the word “tosser” in Top Gear. That Will still has a job at the BBC emphasizes just how incompetent every facet of the company’s management is.

Mostly, though, these characters shine the most when juxtaposed against folks who are both smarter and more cynical than they are. On Silicon Valley, for instance, the amiable Big Head—who can’t help failing upwards—gets increasingly appealing as protagonist Richard’s integrity slowly melts away. The more our ostensible hero embraces his inner heartless tech titan, the more refreshing it is to watch his soft-spoken friend’s less ambitious exploits—like when Big Head has his swimming pool moved, then changes his mind, admitting, “Turns out the guy who built this place knew exactly what he was doing, and the pool was right where it needed to be the whole time. But now I know that for sure, which feels good.”

Sadly, dummies like Todd, Will, and Big Head do not always get their due. They usually hover on the sidelines; their misbegotten adventures can be dismissed as distractions from the main narrative. Just look at poor Joey Tribbiani, who, during the early days of Friends, was so under-appreciated that NBC executives were willing to cut Matt LeBlanc from the cast after its stars collectively argued for a pay raise to $100,000 per episode. (They settled on about $70,000 per episode after NBC callously said it would be fine featuring just five Friends—but later, after the show became a monster hit, they famously bargained for $1 million per episode.)