Fans of Lee Child’s “Reacher” novels had a real problem when his novels were made into movies. And that problem came down to two simple words: Tom Cruise.

Cruise, of course, is a generational movie star and a proven box-office draw. It’s no surprise that when he expressed interest in portraying Child’s protagonist, Child approved. With Cruise on board, the movies – ultimately two of them – garnered an almost-automatic green light.

Alan Ritchson as Jack Reacher in “Reacher.” (Prime Video)

Here’s the thing, though. The essence of Reacher’s character is his size: 6-foot-5 and 250 pounds. His very presence intimidates people, giving him an advantage in a fight – not that the former Army military police officer needs one.

For all his on-screen charisma, Cruise stands a generous 5-7 (Google it), which isn’t likely to intimidate anyone. His success in the “Mission: Impossible” franchise depends more on his brains, and his derring-do stunts, than his size.

When Alan Ritchson – who stands 6-3 and weighs some 230 pounds – ended up being cast in the Amazon Prime series, two seasons of which are now available for streaming, he proved convincing. He’s particularly believable as a character in books that, as one critic opined, “read like ‘Murder, She Wrote’ if the show was fronted by Dolph Lundgren instead of Angela Lansbury.”

With series developer and showrunner Nick Santora working closely with Child, “Reacher” the series is adapted from a pair of novels – 1997’s “Killing Floor” and 2007’s “Bad Luck and Trouble” – over the two seasons.

The first has Reacher (first name Jack but something he seldom, if ever, mentions) arriving in the town of Margrave, Georgia, where he is immediately arrested.

He ends up teaming with a couple of local cops (played by Malcolm Goodwin and Willa Fitzgerald) to both solve his brother’s murder and to break up a local crime operation.

In the second, Reacher is reunited with members of the Army investigative team that he once commanded, the 110th Special Investigations Unit. Their mission is to solve the deaths of some of the unit’s other members and, again, break up a crime operation (led by a character played by Robert Patrick).

Ritchson’s version of Reacher isn’t exactly like that which Child portrays in his novels. He’s more expressive, and he tends to take more of a grim kind of glee in dispensing his version of justice. Reacher in the novels is far more matter-of-fact, if no less violent when violence is called for.

Which calls for the obligatory trigger warning. Pop culture loves its justice-seeking vigilantes, whether they be dressed as a bat or – like Reacher – roam the countryside with barely more than a toothbrush and a passport in their pocket.

Because television is a visual medium, the character in Amazon Prime’s “Reacher” tends to wreak havoc on the villains he faces with the kind of prejudice – from incineration to tossing people out of helicopters from great heights – that is graphic to the extreme.

Give Tom Cruise credit, then. In the two films in which he plays Reacher – 2012’s “Jack Reacher” and 2016’s “Jack Reacher: Never Go Back” – he gets tough with the bad guys, too. But typically he does so in a more muted manner.

So, it’s the Reacher fan’s choice: Size may not be everything, but is it enough? To some of us, the obvious answer is yes.