For Williams, it is another opportunity to equal Margaret Court's Grand Slams singles title record by claiming the 24th of her career, and she will be hoping to go one better than she did at SW19 last year, where she lost to Angelique Kerber in the final.
Halep, meanwhile, will be chasing her second Grand Slam title in her first Wimbledon final; her previous best was a run to the last four in 2014, and she has admitted that it is only this week that she has finally fallen in love with grass.
So who will emerge victorious and pick up the famous trophy Saturday? ESPN's writers and analysts give their view:
Who is under the most pressure: Halep chasing her first Wimbledon, or Serena chasing Slam No. 24?
Halep reaches first Wimbledon final
Simona Halep coasts past Elina Svitolina in straight sets, 6-1, 6-3, to reach her first Wimbledon final.
Brad Gilbert: Serena. I think, more than 24, the number four is more important to her than anything else. There have only been three women who have won a major after having a baby: Evonne Goolagong, Margaret Court and Kim Clijsters. I think joining that list would mean a lot to her. But at this hurdle, where she used to be invincible, Serena has lost four of her last six major finals. But the way she's playing, she has to feel confident because of her 9-1 head-to-head with Halep.
Peter Bodo: The pressure is on Serena because of the historic significance of her assignment. That is going to give Simona Halep a psychological edge that she would not have under almost any other circumstances. But will that be enough to underwrite an upset of the GOAT? Halep has never played a Wimbledon final, so it's going to be terra incognita for her. Williams has been there 11 times, so the greater danger for her is coming up flat. The best thing Halep has had going for her is the blithe, positive attitude she's maintained throughout the second week. She's been sharp and focused on the court, relaxed and congenial off it, and she's proclaimed that she "loves the grass" and feels like she's cracked the turf code.
Alyssa Roenigk: Williams, absolutely. That number has dogged her since the day she won No. 23, and until she wins another Slam, whether she admits it publicly or not, the pressure is there to do what no player has done before her. But she can't win No. 25 without capturing No. 24. Williams has won here seven times, is into her second-straight Wimbledon final and is expected to win. She doesn't want to be known as the player who returned to tennis after the birth of her daughter, made three Grand Slam finals and lost them all. In her favor? Since making her first major final in 1999, Williams has never lost three Slam finals in a row.
D'Arcy Maine: Serena, and it's not close. As much as Halep wants to win her first Wimbledon title, and her second Slam, the average sports fan probably won't think or care all too much if she doesn't achieve that goal this time around. Serena, on the other hand, will be the talk of the sports world whether she wins or loses. To quote the great Billie Jean King, and also a random fan who shouted it at a match the other day, "Pressure is a privilege." There's no one with more pressure than Serena Williams in tennis right now. Especially when you consider the controversial finish to the 2018 US Open, her last major final, it seems like Serena would really like to create some better memories for herself, and her legacy.
Tom Hamilton: The pressure is on Williams. Halep has spoken during this tournament about how she is "chilled out," but do not mistake this for complacency. No, this is her new outlook on life off the court, where she has stopped piling pressure on herself and is instead managing to compartmentalize her life. As Williams seeks to equal Margaret Court's record of 24 Grand Slam singles titles, she will be the one in the spotlight.
Simon Cambers: It has to be Serena. We've seen the way the stress levels rise for Serena when she's close, and though most of her problems have come at the US Open, remember what happened last year, when she was beaten by Kerber. There's no pressure on Halep because no one expects her to win.
Who played better in her semifinal?
Serena dominates in first set
Serena Williams shows off her power in her 6-1 first set win over Barbora Strycova.
Gilbert: Advantage, Serena. Even though it was probably the best match of Halep's career, if Serena plays at the level she did today, there will be no denying her. But I do think there are ways to defuse her game.
Bodo: We have to go with Halep, even though Williams was at or close to her devastating best. Halep had a more accomplished opponent, No. 8 seed Elina Svitolina, who has been ranked as high as No. 3 in the world. She put up stiff opposition, engaging Halep in numerous high-quality rallies that fully tested each woman's skills as well as nerves. Granted, neither Williams nor Halep lost a set, and they surrendered a measly total of just seven games. But Halep won a lot of very close games crafting a win that wasn't nearly as easy as the scores suggest.
Roenigk: They both played lights-out tennis, but Williams not only dominated her opponent but played better than she has in months, surprising no one more than herself. It's hard to find a flaw with her game right now, and her three mixed-doubles matches with Andy Murray only served to add to her arsenal. Her play at the net Thursday was as superb as her rocket-launched returns. Not to mention two 121 mph aces. Fire.
Maine: Is this a trick question? They both played so well there's no wrong answer here. However, there might be a slight edge to Halep because she faced a trickier and more proven opponent in Svitolina. The first game of the first set made it look like it had all the makings of a dramatic three-setter, but Halep then dominated for a 6-1 opener. Svitolina tried her best to fight back -- it was 3-3 in the second -- but Halep seized the moment and won the rest of the way out.
Hamilton: Halep's victory over Svitolina was hugely impressive. It was billed as a match that could be decided on the flip of a coin, but Halep stormed through in straight sets.
Cambers: Serena. She's been improving since Round 1, and after a tight opening to the match, she cut loose. She lost just three points on her first serve and hit 28 winners in all. Halep played very well, but Serena was even more impressive.
For Halep to win, she has to... ?
Gilbert: Two things are crucial. She has to make a high percentage of her first serves. Head to head, it's the second serve where Serena buries Halep, who doesn't have that big of a second serve. And one adjustment I would love to see Halep make is to get back on Serena's serves. Halep tends to do what we saw from Barbora Strycova in the semifinal, and from a lot of women against Serena: They stand on the baseline to return her serve. Simona should put in the video of Kerber in the final last year, when she stood 8 feet back. That seemed to change the dynamic. I would love to see Halep start back and give Serena a different look and try to get into some service points.
Bodo: Pray that Williams won't go on one of her serving sprees, littering the court with aces. She will also have to protect her own service games from the depredations of the deadliest returner in the women's game. What it boils down to is that Halep needs to extend points and work Williams the way a boxer who lacks a knockout punch works over the body of an opponent. Williams is 37. If Halep can keep Williams from taking control of the points with the serve or the return, she might be able to turn the match into a track meet. And if she can open up the court for the down-the-line backhand dart or the inside-in forehand she hits so well, so much the better.
Roenigk: Stay focused, harness her powerful backhand, keep the unforced errors to a minimum. The way Williams is playing this fortnight, only perfect tennis will keep her at bay.
Maine: She will need to control the tempo from the start and make Serena run and generally be as far out of her element as possible.
Hamilton: Play at her best but also nail her first serve. She has the baseline prowess to keep Williams at bay, but she must put Williams on the back foot and play to the corners. She has broken the most serves out of anyone who made the semifinals -- and she continued that dominance against Svitolina -- and she will need more of the same if she is to take down Williams.
Cambers: Nullify the strength of Serena's serve and extend the rallies. The first one will be very hard to do if Serena keeps serving as she has been in her past two matches, but extending the rallies should be possible. Halep's an outstanding athlete, and she can run forever.
For Serena to win, she has to... ?
Gilbert: The two strengths of her game are her serve and her return. She served a lot better Thursday, and she should get lots of looks on Halep's serve, so she has to feel really confident going into the final. Her team has done a good job of putting her into a good position. She's finally healthy and feeling good.
Bodo: Take control and keep Halep from doing what she does best -- run, retrieve, keep rallies going and, ultimately, win points with her counterpunching ability. That means taking the racket out of Halep's hand with some heavy serving. She needs to attack any second serve she sees. Williams shouldn't be too keen to open up the court -- that plays into Halep's run-and-gun style. If Williams keeps the ball deep and in the middle of the court, she'll deny Halep the angles and set herself up for the kind of point-ending placements that have always been her stock-in-trade.
Roenigk: Overpower Halep, stretch her from sideline to sideline and shorten the points. And maintain the calm Williams said she woke up with before Thursday's semifinal match.
Maine: Serena has lost the two major finals she's played in since her return from the birth of her daughter, so she is going to need to stay mentally strong and forget about both of those matches. She needs to stay completely focused on this one match and not everything that surrounds it. If she can play her dominating brand of tennis, and remain immune to the outside noise, this is her title to win.
Hamilton: Get a foothold early in the match and not let it slip. Halep has been talking up the strength in her legs and her new appreciation of how she can make the ball move on grass, so Williams must unsettle her early on and then keep a viselike grip on the match. She must be wary of Halep's return, but if she gets that jackhammer backhand going, then Halep will need to find a way to nullify that threat.
Cambers: Serve well and hold her nerve. We've seen how stressed she can get on the verge of this historic win, but if she serves well, the rest of her game will flow, which should make handling the situation easier.
What is your prediction for the final?
Gilbert: I'm hoping for a good match. I would love nothing more than to see it go to three sets, 7-5, 8-6 in the third, a classic match. I think we need one. But if this were a football game, Serena would be a 10-point favorite.
Bodo: Serena was in a similar situation in last year's final against Angelique Kerber, who ended up shocking most pundits -- as well as Williams -- by playing lights-out tennis and denying Williams the win. She will be extra alert and super eager to get the No. 24 major title that everyone but Williams keeps talking about. She knows what pressure is all about. She won't let this one slip away.
Roenigk: Williams heads to the US Open in New York, where the questions turn to whether she'll win No. 25 there. She wins in three sets here Saturday.
Maine: Serena owns a 9-1 career record over Halep, but all three of their previous meetings at Slams have gone three sets (including most recently at the Australian Open in January). I think that's exactly what will happen here -- Serena wins No. 24 (ahhh!) in three.
Hamilton: Halep will come through in three sets in a match for the ages.
Cambers: Serena to win in two sets.