Head-hunters, rib-crackers, leg-whippers and knee-busters.

They are out there every NFL Sunday, and a few on Monday night, too. They are the late hitters and low roaders of pro football.

Like Andre Waters, the Philadelphia Eagles strong safety, who drove his helmet into Minnesota quarterback Rich Gannon’s knees before an outraged TV audience a few Mondays ago.

Tonight at 8, at Joe Robbie Stadium, the much-maligned Mr. Waters tunes his homing device on quarterback Dan Marino.

Some call Waters a cheap-shot artist. Others call him a doggone good football player.

Whatever he is, if coach Buddy Ryan has done his job preparing, Waters and his nefarious teammates will be on their worst behavior.

Dan Dierdorf, the colorman for the Monday Night Football telecasts, calls Waters “a dirty player.”

But, said Andy Hinson, Waters’ college coach: “If you knew Andre like I do, you would want your son to be just like him. He’s quiet, he doesn’t drink, he doesn’t smoke, he’s well-mannered and he helps those in need.”

Gee, you’re thinking, what a sweetheart.

Steve Bartkowski, a former great quarterback, wouldn’t quite see it that way. He was in the sunset of his career in 1986 when he was with the Los Angeles Rams. With one shot to the knees, Waters speeded his retirement.

And there was the David Archer hit. And the fight with Doug Williams. Also the hits on Dennis McKinnon and Jim Everett. You could go on and on. Just consult your blood-spattered Eagles schedule for the past five years.

Waters is at the top of everyone’s list of marginal hitters, those who always seem to deliver their blows about two Mississippis after the seventh whistle.

There is Scott Case of the Falcons, Jessie Small of the Eagles and Ronnie Lott of the San Francisco 49ers.

Too many of their tackles seem to be helmets to the knees or ribs or a forearm to the head.

Most of them are safeties, who can rev up a flying run to the pile. The NFL tries to control their behavior with fines. Waters was nicked $10,000 for the Gannon hit.

But what are players supposed to do when you have coaches like Jerry Glanville of Atlanta saying of dirty guy Greg Lloyd of Pittsburgh: “He’s mean, he’ll cheap-shot you, hit you behind the head, do whatever he wants. I love him.”

Waters is one of 14 children who grew up in a single-parent family in poverty-punctuated Belle Glade. He was lucky to get into little Cheyney University near Philadelphia.

“A friend of mine recommended him, and we brought him up here,” said Hinson. “And he didn’t get one brown penny. We don’t give scholarships.”

Signed as a free agent by the Eagles in 1984, Waters didn’t have much of a career until Ryan came to Philadelphia in 1986. Then, wham. It was like someone unharnassed a knee-seeking missile.

“The more Buddy encouraged him, the worse Andre got. I think Buddy sort of smirked about it, figuring he could get him to run through a wall for him,” said Dolphins linebacker Mike Reichenbach.

Reichenbach goes back a long way with Waters. He played at East Stroudsburg University when Waters was at Cheyney. “Same league,” said Reichenbach, who signed as a Philly free agent the same year as Waters.

Reichenbach moved to Miami on Plan B this season. “Andre was a cornerback in college, so he didn’t get to hit as much. And when Buddy came to the Eagles, he was a special-teamer. But Buddy encourages aggressive attitudes in his players and Andre really pushed it. It got so bad he was hitting his own teammates in practice trying to break into the starting lineup.

“He’s like a seek-and-destroy guy who doesn’t control his aggression. He goes at just one speed and it wasn’t totally appreciated at the Eagles,” Reichenbach said.

Hinson, who understands Waters’ roots, had a little different perspective. “To tell you the truth, Andre’s hometown is about the size of my office,” he said. “His mother worked in a sugarcane mill in Pahokee. If a kid had a choice of going back to that or playing in the NFL, I think I know what he is going to pick. If that’s what I had to go back to, I’d hit like hell, too.”

Whether Waters and the other toughs of the NFL are “dirty players” depends a lot on your feelings about pain. Pro football is, after all, about as primitive as rollerball.

Sometimes the only thing separating a dirty play from a clean hit is about 1 1/2 seconds. It isn’t the act that makes a play dirty. It’s when.

Last Monday night, Lott jolted New York Giants tight end Mark Bavaro with a crushing blow to the head on an incomplete pass. There was no flag, though many considered it close or, indeed, a late hit.

The same hit, if Bavaro had held the ball, would have been exalted as great football.

Cheap shots don’t have to be forearms or helmets. Defensive end Dexter Manley, when he was with Washington, spat on tackle Jim Dombrowski of the Saints. Sean Jones, when he was with the Raiders, did the same to 49ers tackle Bubba Paris. Dombrowski called Manley “Mr. Raunch.” Paris said of Jones: “A lowlife thing to do.”

Seldom is an offensive lineman accused of cheap-shotting, but the Niners have achieved a reputation for leg-whipping over the years, deliberately tripping defenders as they rush across the line of scrimmage. It can be dangerous.

Guard Bruce Collie, with the 49ers in 1989, was accused by Denver coach Dan Reeves of leg-whipping his star linebacker, Karl Mecklenburg, out of Super Bowl XXIV last January. Mecklenburg needed knee surgery. Collie is now a backup for the Eagles.

Waters may be the preeminent dirty player in the NFL, but no one has achieved as much status for extracurricular hitting as former offensive lineman Conrad Dobler, author They Call Me Dirty.

“A lot of what people call dirty plays is just intimidation,” Dobler said. “And what’s wrong with intimidation? The U.S. government is using intimidation right now in Saudi Arabia.

“Look, it’s a violent game, and you’d better be a violent individual. I’ve had Lyle Alzado, Jack Youngblood and Merlin Olsen try to break my legs. I’m not crying about it. It’s part of the game.

“Now, this guy Waters… Do I think jumping over someone to hit him in the knees is dirty play? Do I think shoving a helmet into someone’s ribs is dirty play? Do I think reaching out and putting an elbow in someone’s facemask is dirty play?

“No.”

Dobler long ago came to grips with low blows and late shots. “That’s life.”

NFL’S DIRTY DOZEN

1. Strong safety Andre Waters, Eagles: Understands the anatomy of the knee and how to make it dysfunctional.

2. Safety Scott Case, Falcons: Blindsides receivers over the middle. This year he strafed Ernest Givins’ head after the Oilers receiver had laid out trying to make a catch. Once smacked 49ers receiver Freddy Solomon in the head, knocking him out, on a ball overthrown by 10 yards. What the heck. It was a free shot.

3. Linebacker Greg Lloyd, Steelers: Wears a T-shirt with a skull and crossbones and the word Caution below it. On the back of the shirt: I wasn’t hired for my disposition. Last season, after a teammate knocked Jets receiver Al Toon into dreamland, Lloyd got down on his knees and slammed his fist into the turf, as if counting him out.

4. Safety Ronnie Lott, 49ers: Gets away with a lot of late hits, many players believe, because he is bound for the Hall of Fame. Lott had at least one, maybe two marginal licks on Giants tight end Mark Bavaro in last week’s Monday night game.

5. Offensive lineman Bruce Collie, Eagles: Master of the leg-whip. It wasn’t surprising Buddy Ryan would sign him after he was waived by the 49ers.

6. Linebacker Jessie Small, Eagles: Specializes in wiping out defenseless kickers. Small, 240 pounds, once went after Cowboys’ Luis Zendejas, 169 pounds, after a kickoff.

7. Linebacker Jimmy Williams, Vikings: Cut loose by the Lions last week after his dirty shot to quarterback Jim Harbaugh’s head in the Bears game cost Detroit a critical penalty.

8. Safety Alvin Walton, Redskins: Could get a job on the border patrol when he’s out of football. Always treading the line between clean and not-so-clean. “Get off my back,” Waters once told Washington reporters. “You’ve got your own guy over there.”

9. Safety Mike Harden, Raiders: Trying to clean up his act after he was nicked $5,000 when he was with the Broncos and smacked Seattle receiver Steve Largent in the head, causing a severe black eye. It’s not that easy to be Mr. Nice Guy when you’re a Raider.

10. Defensive end Dexter Manley, Cardinals: Lets his saliva do the talking. Once spat upon Saints lineman Jim Dombrowski.

11. Safety Kenny Hill, recently released: When he was with the Giants, he once ran 25 yards after an incomplete pass to spear prostrate 49ers receiver Jerry Rice in a playoff game.

12. Nose tackle Charles Martin, recently released: He’ll live with his foul shot on Jim McMahon the rest of his life. Then with the Packers, Martin came around behind the Bears quarterback long after the pass was gone, picked him up and drove him, shoulder down, into the ground.