When some MLB hitters step into the batter’s box, pitchers take careful notice. They are the rare players who can live inside a pitcher’s head and leave them scrambling to find a way to get them out.

For pitchers, it’s a completely different mindset when you face one of these hitters. They stand on the mound knowing they can’t make a single mistake. If they do, they’ll become another name on a long list of players these hitters have taken deep.

Of course, it’s not only about power. Some of the game’s most intimidating players can kill a pitcher’s focus with their speed on the bases.

Here are the 10 MLB hitters who strike the most fear into opposing pitchers.

Mookie Betts, outfielder, Boston Red Sox

When an opposing pitcher opens their calendar and notices they have to pitch against Boston, their head has to drop. Boston’s lineup is loaded across the batting order with threats to get base hits, home runs or stolen bases. Yet even in a lineup as strong as this, no one touches Betts presence in the batter’s box.

Betts is the best player in baseball this season with a league-high 17 home runs, .361 batting average, 1.199 OPS and the third-most stolen bases (13) through 48 games. He’s doing things Boston has seen only twice before in its storied history. The challenge of facing a 25-year-old with 37 of his 65 hits going for extra bases can be daunting for a pitcher.

It doesn’t matter if you’re a southpaw — Betts has a 1.326 OPS versus lefties — or a right-handed pitcher (1.158 OPS), no pitcher is safe against Betts. The problem is, it’s difficult to even justify walking him. If a pitcher does that, Betts can steal second and put a runner in scoring position for Andrew Benintendi and J.D. Martinez.

Simply put, it’s a no-win situation for pitchers. When a hitter leaves you with that feeling, it can be awful for a pitcher’s confidence.

Mike Trout, outfielder, Los Angeles Angels

In the race for the American League’s MVP award, Trout is right on Betts’ heels. In the contest for which hitter is more intimidating to opposing pitchers, it’s a tie between the All-Star outfielders.

While Trout’s .293 batting average would be his worst mark since 2014, it’s saying something when that mark is considered low for him. This season, we’ve seen the fear of facing Trout turn into an even more extreme approach for pitchers. The 26-year-old, who never walked more than 116 times in a season, is on pace for 150-plus walks in 2018.

Even when pitchers try and work around Trout, the two-time MVP winner crushes them (like this). In 174 at-bats, the center fielder has 16 home runs, 30 RBI and 12 stolen bases. The veteran is also quickly adjusting to the new pitching approach used by opposing teams and his OPS has improved each month from 1.063 in April to 1.162 in May.

It doesn’t matter what a pitcher does, Trout will defeat them and it shows in his league-leading .449 on-base percentage. If he continues to get on base, Trout can deliver a 50-40 season.

Aaron Judge, outfielder, New York Yankees

Aaron Judge home run New York Yankees

Of course the man who set the record for most home runs by a rookie (52) belongs here. While the 26-year-old may not be receiving quite as much of the spotlight this season, he is making opposing pitchers uneasy on the mound.

The right fielder gets on base at a ridiculous level (.409 OBP) and continues to crush baseballs right and left with 13 home runs and 11 doubles. It’s more than just his numbers alone that make him intimidating, he is also a massive human being.

At 6-foot-7 and 282 pounds, Judge’s physical presence alone can be intimidating for pitchers. With so much muscle packed into his frame and a natural swing, even the slightest missed location on a pitch could turn into a baseball screaming off the bat at 115-plus mph into the second deck of Yankee Stadium. Judge is one of the last people a pitcher would want to face in a dark alley or in the batter’s box.

Manny Machado, shortstop, Baltimore Orioles

Shortstops don’t often make it on these lists, but Machado is a different player. In his age-25 season, the right-handed batter is showing why he will be the most sought-after player at the MLB Trade Deadline.

When Machado is traded, his future teammates on the mound will be ecstatic. For at least a few months, the pitchers can rejoice at not having to face a batter with 15 home runs, a .328 batting average and a 1.023 OPS this season.

What makes those numbers even more impressive is it’s being done without much lineup protection. Opposing pitchers can at least pitch a little more relaxed knowing Machado doesn’t have a Justin Upton, Giancarlo Stanton or J.D. Martinez behind him, but that will change later this year.

For the divisional foes of the team that lands Machado, a sinking feeling will set in the day they look at their phone and see Machado landed in the division. Once Machado gets some help behind him in the lineup, things could get even better for him.

Freddie Freeman, first baseman, Atlanta Braves

In a lineup where Ozzie Albies and Ronald Acuna have drawn the attention, Atlanta’s first baseman remains one of the game’s best hitters. His impact is even more meaningful now thanks to the presence of the young hitters in front of him.

Beyond Freeman’s outstanding .328/.428/.548 line this season are his numbers with runners in scoring position. Just think about it for a second. A pitcher just surrendered at least one base runner and with a runner now in scoring position, now Freeman steps into the box. According to ESPN, it’s an all too familiar feeling for pitchers this year given Freeman’s numbers in 44 at-bats. Freeman owns league-leading .409 batting average with runners in scoring position. The 28-year-old also ranks third in OPS (1.176) and second in slugging percentage (.705) in these situations.

Freeman is the force that really drives this offense and comes up clutch when Atlanta needs a hit the most. For opposing pitchers, there is nothing they fear more than a great hitter with runners on base.

Jose Ramirez, third baseman, Cleveland Indians

For a small stretch to begin this season, a sliver of hope and confidence existed for pitchers facing Ramirez.

In his first 10 games this season, the 25-year-old registered a .085 batting with two singles and one home run. Perhaps for a split second in time pitchers enjoyed the moment. They certainly should have given the third baseman has destroyed nearly every pitcher faced since.

Since that stretch, Ramirez carries a .342/.422/.697 slash line with 15 doubles, 13 home runs, 31 RBI and 29 runs scored. He is one of the game’s most patient hitters and seems to read each ball out of a pitcher’s hand as if it arrives in slow motion.

When a batter is this locked in, pitchers are often left discombobulated. They can only hope Ramirez doesn’t square the ball up and hits a sharp liner to an outfielder or grounds out sharply for a quick out. Unfortunately for pitchers, that doesn’t happen too often against Ramirez.

J.D. Martinez, outfielder, Boston Red Sox

It’s simply baffling that so few teams pursued Martinez this offseason. Not only is he a player who can significantly improve a team’s offensive output, but it would also keep your own pitchers from having to face him.

Boston did land him and is enjoying the rewards this season. The 30-year-old has baseball’s second-highest slugging percentage (.653) this season, the second-most RBI (42), home runs (16) and the third-best OPS (1.037) in the majors.

While he is overshadowed by his own teammate (Betts), there isn’t a pitcher on earth who forgets about Martinez when they are scouting Boston’s lineup. Pitchers across baseball are asking themselves why their front office didn’t sign one of the game’s best hitters, a move that would have provided them run support and kept them from having to face this All-Star hitter.

Bryce Harper, outfielder, Washington Nationals

Bryce Harper

It says something about Harper that he remains on this list despite experiencing one of the worst seasons in his career. A .237 batting average isn’t impressive by any means, yet Harper’s other numbers show this is still a player pitcher just don’t like facing.

The 25-year-old is on pace for a career-high in walks this season and, despite the low batting line, his .387 on-base percentage is impressive.

When Harper gets a hit, the safe bet is it will go for extra bases. Of his 40 hits this season, 15 were home runs and six were doubles. Given those numbers, it’s easy to see why pitchers still feel a little queasy facing him and will often still try and pitch around him despite the poor batting average.

That is the mark of a feared hitter and the impending free agent should turn things around soon, which will make him even more of a nightmare for pitchers.

Nolan Arenado, third baseman, Colorado Rockies

Similar to Ramirez, Colorado’s star third baseman gave opposing pitchers a little time this year to settle in and seemingly build up some faux confidence. Then once the weather warmed up and things started clicking, he crushed their dreams.

A perennial All-Star, the 27-year-old is turning things up as the calendar moves forward. After he posted a .311 batting average, .515 slugging percentage and .943 OPS in April, Arenado’s numbers in May are on the rise with a .329 batting average, .585 slugging percentage and 1.000 OPS.

While pitchers can get away with more on the road, Coors Field is this man’s home and no one can stop him. In 66 at-bats in Denver this season, Arenado carries a .394/.481/.667 slash line with a 1.148 OPS. Now with the Rockies set to play more home games in the coming months, Arenado’s numbers should continue to rise and pitchers will continue to loathe everything about facing Colorado.

Jean Segura, shortstop, Seattle Mariners

This name will certainly surprise a few, but Segura’s 2018 season demonstrates why he is one of the last players a pitcher wants to face right now.

It’s a layered approach with the veteran shortstop, who is enjoying another excellent season. The 28-year-old carries a .316/.333/.445 slash line through 48 games, and his numbers are up to .339/.350/.464 in the last 30 days.

Of course, this is about more than base hits for Segura. Among players with 90-plus at-bats with runners on base, Seattle’s shortstop has the second-highest batting average (.347) in those situations. He also has the sixth-most RBI (32) with runners on base.

Segura’s threat to pitchers doesn’t just stop in the batter’s box. He is a menace on the basepaths who capitalizes on the slightest opportunity to take off and steal second base. Sometimes, he’ll take things a step further and attempt to steal third.

His work on the bases and in the batter’s box this season helps him live in the pitcher’s head each time they face off and the carryover influence with his speed helps his teammates while they are batting.