Spencer Strider ended the 2023 regular season with 281 strikeouts, setting a new Modern Era record for the Braves. Strider unseated John Smoltz, who struck out 276 batters in 1996.

The Braves are one of several franchises to see new marks in recent years. Gerrit Cole became the Yankees’ single-season strikeout leader in 2022, three years after breaking the Astros’ record.

Here is each team’s single-season strikeout record in the Modern Era (since 1900).

American League East

Blue Jays: Roger Clemens, 292 (1997)

At age 34, Clemens experienced a career resurgence in his first season with the Blue Jays. He went four years without an All-Star appearance from 1993 to 1996 but changed that and then some the following season: an MLB-leading 264 innings, 292 K’s and a 2.05 ERA. Clemens won the 1997 AL Cy Young Award -- then won another the following year, the fifth of his career. He went on to win two more in 2001 and 2004.
Runner-up: Clemens, 271 (1998)

Orioles: Rube Waddell, 232 (1908 St. Louis Browns)

In 1908, Waddell came to the St. Louis Browns -- later the Orioles -- from the Philadelphia Athletics and had one of the best years of his Hall of Fame career. Waddell posted a 1.89 ERA in 285 2/3 innings, striking out 232 hitters and not allowing a single home run. More than 100 years later, his strikeout record still stands. Erik Bedard leads the way since the team became the Orioles in 1954, fanning 221 batters in 2007.
Runner-up: Bobo Newsom, 226 (1938 Browns)

Rays: Chris Archer, 252 (2015)

Archer owns three of the top five single-season totals in the Rays’ relatively short history. He set the top mark with 252 K’s in 2015, his first All-Star season, then followed it up two years later with 249 (despite a 4.07 ERA) in another All-Star campaign, his final full season with the Rays.
Runner-up: Archer, 249 (2017)

Red Sox: Pedro Martinez, 313 (1999)

It’s hard to pick the best season of Martinez’s Red Sox career, but 1999 is certainly a contender. In his age-27 campaign, Pedro won an MLB-leading 23 games, posted a 2.07 ERA and won his second Cy Young Award. He fanned 313 batters in 213 1/3 innings for a ridiculous 37.5% strikeout rate. Among other Red Sox pitchers, only Chris Sale in 2017 has broken the 300-strikeout mark.
Runner-up: Chris Sale, 308 (2017)

Yankees: Gerrit Cole, 257 (2022)

In the Yankees’ long history, no pitcher had ever surpassed 250 strikeouts in a season -- until Cole did it in 2022 in his third season in pinstripes. Cole’s first year produced 243 strikeouts, five short of Ron Guidry, who fanned 248 amid a fantastic Cy Young Award-winning 1978 season: 25-3, nine shutouts and a 1.74 ERA in 273 2/3 innings. He topped that mark in 2022 to pass Guidry.
Runner-up: Ron Guidry, 248 (1978)

AL Central

Guardians: Bob Feller, 348 (1946)

Feller’s 1946 campaign was his first full season since returning from serving in World War II, and it was one for the ages. Starting 42 games that year, he led the Majors with nearly 350 strikeouts -- despite leading the way with the most hits and walks allowed, too. Feller threw 36 complete games, including 10 shutouts. Sam McDowell holds second, third, fourth and fifth place in franchise history -- all between 1965 and 1970 -- but could never pass Feller.
Runner-up: Sam McDowell, 325 (1965)

Royals: Dennis Leonard, 244 (1977)

Leonard set the Royals’ single-season record during his fourth-place AL Cy Young Award campaign in 1977. The veteran, who spent every one of his 12 seasons with Kansas City, struck out 244 batters in 292 2/3 innings to pass Bob Johnson (206 strikeouts in 1970). Zack Greinke got within two strikeouts of Leonard’s record in 2009 -- in more than 60 fewer innings.
Runner-up: Zack Greinke, 242 (2009)

Tigers: Mickey Lolich, 308 (1971)

Lolich arguably had his best season in 1971, topping 300 strikeouts for the first and only time across 45 starts -- including 29 complete games -- with the Tigers. It still wasn’t enough for Lolich to win the AL Cy Young Award, which went to Vida Blue of the A’s. The closest anyone has come to Lolich’s record since was Justin Verlander in 2009 with 269 strikeouts.
Runner-up: Denny McLain, 280 (1968)

Twins: Walter Johnson, 313 (1910 Washington Senators)

Who else but Johnson, one of the greatest pitchers ever, to lead the way for this franchise? Johnson wasn’t around by the time the Twins moved to Minnesota in 1961, but he had a pair of 300-strikeout seasons for their precursor, the Washington Senators. Johnson’s record from 1913, a year in which he posted a 1.36 ERA, still stands. Since the move, Johan Santana (265 strikeouts in 2004) has come the closest to unseating Johnson, but it’s a high bar to clear.
Runner-up: Johnson, 303 (1912 Senators)

White Sox: Chris Sale, 274 (2015)

Before Sale debuted with the White Sox, no one had even come close to Ed Walsh’s record of 269 strikeouts back in 1908 -- a mark that appears less impressive considering it was accomplished in 464 innings. Sale now has three of the top 10 seasons in White Sox history, including the No. 1 spot -- accomplished in the fourth of his seven consecutive All-Star seasons.
Runner-up: Ed Walsh, 269 (1908)

AL West

Angels: Nolan Ryan, 383 (1973)

The top five strikeout seasons in Angels history? Ryan, Ryan, Ryan, Ryan and Ryan -- all between 1972 and 1977. Ryan reached his strikeout peak in 1973, fanning 383 hitters in 326 innings to go with a 2.87 ERA. He holds the Modern Era record for strikeouts in a single season -- not out of character for the man who finished his 27-year career with an MLB-record 5,714 strikeouts.
Runner-up: Ryan, 367 (1974)

Astros: Gerrit Cole, 326 (2019)

Cole doesn’t just hold the Yankees’ single-season record; in 2019, he broke a 40-year-old mark previously held by J.R. Richard. Richard had two of the Astros’ three 300-strikeout campaigns prior to 2019, when TWO pitchers reached that milestone -- Cole and Verlander. Verlander wound up with exactly 300 strikeouts, but Cole finished with 326 to pass Richard for the top spot.
Runner-up: J.R. Richard, 313 (1979)

Athletics: Rube Waddell, 349 (1904 Philadelphia A’s)

Waddell is another of the pitchers who holds multiple teams’ records, this one set in the early -- read: Philadelphia -- days of the Athletics franchise. In 1903, the club’s third season ever, Waddell struck out 302 hitters; the following year, he upped that total to 349. Vida Blue's previously mentioned Cy Young-winning 1971 season (301 strikeouts) is tops in the team's Oakland era.
Runner-up: Waddell, 302 (1903 Philadelphia A’s)

Mariners: Randy Johnson, 308 (1993)

Three pitchers hold the top 15 spots on the Mariners’ list: Johnson, Mark Langston and Félix Hernández. Johnson has each of the top three, set in alternating years -- 1993, 1995 and 1997. Johnson has the only 300-strikeout season in Mariners history, although he finished with 329 strikeouts in 1998, when he was dealt to the Astros at the Trade Deadline.
Runner-up: Johnson, 294 (1995)

Rangers: Nolan Ryan, 301 (1989)

Oh, hey, it’s Ryan again. Maybe it’s little surprise he owns the only 300-strikeout campaign by a Ranger, fanning 301 hitters in his first season with Texas -- at age 42! Ryan led MLB in strikeouts and was named an All-Star for the eighth and final time. Only two players -- Yu Darvish in 2013 (277) and Lance Lynn in 2019 (246) -- are even somewhat close to Ryan’s Rangers record.
Runner-up: Yu Darvish, 277 (2013)

National League East

Braves: Spencer Strider, 281 (2023)

Strider, in his age 24 season, broke John Smoltz's 27-year-old Braves franchise record when he recorded his 277th strikeout in his final start of the 2023 season. The right-hander would end his campaign, ultimately, with 13.5 strikeouts per nine, also the highest in Braves franchise history, surpassing the previous record of 10.7 held by Charlie Morton (2022).
Runner-up: Smoltz, 276 (1996)

Marlins: José Fernández, 253 (2016)

Fernández died tragically at age 24 with one week remaining in the 2016 regular season. He’d already broken the Marlins’ season record handily, earning the second All-Star nod of his career; the first came in his 2013 NL Rookie of the Year campaign. With 207 strikeouts in his 2022 Cy Young Award-winning season, Sandy Alcantara ranks third in Marlins history.
Runner-up: Ryan Dempster, 209 (2000)

Mets: Tom Seaver, 289 (1971)

Seaver set the Mets’ record in a stellar 1971 season. Pitching to career-lows in ERA (1.76) and WHIP (0.95), he led the National League in strikeouts with 289 -- Lolich and Blue each topped 300 on the AL side. Seaver won his third NL Cy Young that season, part of a string of 10 All-Star appearances in 11 seasons.
Runner-up: Seaver, 283 (1970)

Nationals: Pedro Martinez, 305 (1997 Montreal Expos)

The 1997 season is another contender for Martinez’s best. In his final season with the Expos, he pitched to a 1.90 ERA, throwing 13 complete games in 31 starts -- tied for third-most since 1990 -- and winning his first Cy Young Award. His 305 strikeouts that season remain the most in franchise history; Max Scherzer leads the way since the Expos became the Nationals in 2005 with a 300-strikeout 2018 campaign.
Runner-up: Max Scherzer, 300 (2018)

Phillies: Curt Schilling, 319 (1997)

Schilling posted back-to-back 300-strikeout seasons during his peak with the Phillies, following up his MLB-leading 319 K’s in 1997 with an even 300 the following year. His 1997 total passed Hall of Famer Steve Carlton, who posted 310 strikeouts with a 1.97 ERA in 1972 to win the NL Cy Young. Zack Wheeler (247 K’s in 2021) is the closest Phillie this century to Schilling’s mark.
Runner-up: Steve Carlton, 310 (1972)

NL Central

Brewers: Ben Sheets, 264 (2004)

Sheets was a four-time All-Star for the Brewers, but his 2004 season was a cut above. Sheets finished with a 2.70 ERA and 264 strikeouts -- 94 more than he had in any other season. He finished eighth in NL Cy Young Award voting, his only time receiving any votes. Recently, Corbin Burnes got within striking distance of Sheets’ record with 243 strikeouts in 2022 but could not surpass the mark.
Runner-up: Corbin Burnes, 243 (2022)

Cardinals: Bob Gibson, 274 (1970)

Gibson holds the top six strikeout seasons in modern Cardinals history, with Jack Flaherty (231 strikeouts in 2019) seventh. His 17-year career with St. Louis featured nine seasons of 200-plus K’s. While 1968 was Gibson’s memorable 1.12-ERA season, he racked up six more strikeouts in 1970, totaling 274 for a record that still stands more than 50 years later.
Runner-up: Gibson, 270 (1965)

Cubs: Fergie Jenkins, 274 (1970)

Exactly like Gibson, Jenkins set his franchise’s record with 274 strikeouts in 1970. The two pitchers tied for second in the NL in K’s behind Seaver (283); Jenkins finished third in NL Cy Young voting behind Gibson and Gaylord Perry. He topped his strikeout total from 1969 by just one. Kerry Wood (266 K’s in 2003) came the closest anyone has gotten to Jenkins’ record since.
Runner-up: Jenkins, 273 (1969)

Pirates: Bob Veale, 276 (1965)

One of only a few lefties on this list, Veale reached 250 strikeouts in his first full season, 1964. The following year -- in 13 2/3 fewer innings -- he topped that mark with 276 to set a Pirates record that still holds up. The 1965 campaign was the first of two consecutive All-Star seasons for Veale. Another lefty in Oliver Pérez, with 239 strikeouts in 2004, is the closest pitcher to Veale’s record.
Runner-up: Veale, 250 (1964)

Reds: Mario Soto, 274 (1982)

Soto set the Reds’ record in 1982, the first of three straight All-Star seasons. In his age-25 campaign, he led the Majors in WHIP despite trailing Carlton by 14 strikeouts for the NL and MLB leads. He struck out just 242 batters the following year, but Soto might have been even better in 1983, lowering his ERA and finishing second in NL Cy Young Award voting.
Runner-up: Jim Maloney, 265 (1963)

NL West

D-backs: Randy Johnson, 372 (2001)

Johnson’s Mariners-record strikeout total is impressive, but his numbers with the D-backs were otherworldly. In four straight seasons from 1999 to 2002, Johnson never had fewer than 334 strikeouts; he topped out at 372 in 2001, the year Arizona beat the Yankees in an epic seven-game World Series. Schilling came the closest to Johnson with 316 K’s in 2002.
Runner-up: Johnson, 364 (1999)

Dodgers: Sandy Koufax, 382 (1965)

Koufax’s 382 strikeouts during a magnificent 1965 season are second in the Modern Era to only Ryan’s 383. He posted a 2.04 ERA that year, his penultimate season in the Majors, and won the NL Cy Young Award for the second time; Koufax won his third and final Cy Young in 1966 before retiring at age 30. Koufax has four of the Dodgers’ top-five strikeout marks, with Clayton Kershaw (301 K’s in 2015) holding the other.
Runner-up: Koufax, 317 (1966)

Giants: Christy Mathewson, 267 (1903 New York Giants)

In his age-22 season with the New York Giants, Mathewson set a record that still stands 120 years on -- although not by much. Tim Lincecum struck out 265 hitters in 2008, setting the San Francisco-era record but coming up just two strikeouts shy of Mathewson. Mathewson went on to a Hall of Fame career, retiring with a 2.13 ERA and two pitching Triple Crowns in his 17 seasons.
Runner-up: Tim Lincecum, 265 (2008)

Padres: Kevin Brown, 257 (1998)

A six-time All-Star, Brown led the National League in ERA twice -- but his best-ever strikeout year wasn’t one of those two seasons. In 1998 -- his only year with the Padres -- he struck out 257 batters to set a franchise record, finishing behind Tom Glavine and teammate Trevor Hoffman in NL Cy Young Award voting. Joe Musgrove (203 K’s in 2021) is the only Padre to top 200 strikeouts since 2015, but Blake Snell is on pace to get there in 2023.
Runner-up: Jake Peavy, 240 (2007)

Rockies: Germán Márquez, 230 (2018)

Only three Rockies pitchers have topped 200 strikeouts, a tough milestone to hit -- playing home games at hitter-friendly Coors Field doesn’t help pitchers go deep into games. Márquez was the latest to reach that milestone, surpassing Ubaldo Jiménez and Pedro Astacio by reaching 230 K’s in his age-23 season in 2018.
Runner-up: Ubaldo Jiménez, 214 (2010)