Pete Alonso is the greatest power hitter in Mets history.

He is not the franchise leader in homers, yet no one in the club’s six-plus decades has hit them as frequently or forcefully. The Mets got the last few seasons of Mike Piazza’s high-end might and the opening flex of Darryl Strawberry.

But Alonso has not just homered like no one in Mets history.

In a 6-3 Mets victory Sunday against the Mariners, Alonso hit his 40th and 41st homer of 2023. It was the third time he reached 40 in his first five seasons.

The others to do it are Ralph Kiner [the only one to do it four times], Ryan Howard, Eddie Mathews and Albert Pujols.

End of list.

When told of the company he is keeping, Alonso said, “Holy s–t.”

And remember that Alonso hit 37 in his other full season and 16 in the 60-game pandemic 2020, which prorates to 43 for a full year. As it is, he has three 40-homer seasons as a Met while every other player in franchise history added up has three — one each for Carlos Beltran, Todd Hundley and Piazza.

“He does things that make your jaw drop,” said Brandon Nimmo.

The first Alonso homer was 115.6 mph, marking his 18th homer of at least 110 mph — only Shohei Ohtani (21) has more in 2023. Alonso also had a run-scoring single in a four-RBI game that gave him 100 in a season for the third time. Only David Wright (four) has done it more often for the Mets. Beltran and Strawberry did it three times each.

Pete Alonso circles the bases after his two-run home run on Sunday.

Alonso’s next homer — and he has 25 games to do it, so doh — will give him the second-most in a season for a Met, eclipsed only by the MLB rookie record 53 he hit in 2019.

It is all part of a litany that connects him to franchise history as much as nearly any position player in the club’s lore.

“It kind of just happened so fast,” Alonso said. “It seems like yesterday I was in my rookie season, but it’s my fifth year and time flies.”

Which leads to the bigger story for Alonso and a non-contending team that already has conceded that next year’s club will have lower World Series-winning odds at the outset than this year’s team. Time flies and Alonso will be in his walk year in 2024 and attempts so far to reach a long-term extension have not really come close.

It is why the Mets had Alonso out on the market at the trade deadline and probably will again this offseason. They set a high price for a return in July/August and will do so again this winter. Because Alonso, to date, has set a high price for an extension that even Steve Cohen — who paid market-plus to retain Nimmo, Edwin Diaz and Jeff McNeil — has yet to approve.

But with each homer — each step further into the record book — does Alonso make himself harder to trade? Harder to not keep long-term? Cohen did not make his riches without the ability to coldly assess a market. But he also has shown a tether to this fan base, which certainly will be angered if Alonso is not a lifetime Met.

Part of that acknowledgment of the fans is to retire Strawberry’s No. 18 next year. The Mets allowed Strawberry to exit as a free agent after the 1990 season as the Mets’ all-time homer leader (252).

But there were off-field issues that helped drive that decision. Buck Showalter described the opposite with Alonso — a player who yearns to find ways to improve his total game, a player who is tough and durable.

Showalter also has long admired players and teams that could follow excellence with excellence. The Mets as an organization have not done that. They have never won the division in successive years, never made the playoffs three years in a row and followed 101 wins last season with the most expensive flop in MLB history.

But Alonso’s power is undeterred, though, as Francisco Lindor said, “It is tougher because they know you hit them and there are days that [opponents] are just not going to let you beat them.”

Still, for his career, Alonso has averaged a homer every 13 at-bats. Next best in Mets history is Dave Kingman (15.1), then Strawberry (15.5), then Piazza (15.8).

“In some ways, it is not hard for him because he is so strong,” Nimmo said. “He strikes some balls and it would be a double for most guys, but his just never come down. That’s not extra effort. That’s just his swing.”

It has landed him as a constant in the Mets record book.

Will it land him a long-term deal here?