Is there a way to grapple as a bonus action without attacking first?

Question

I know there are some ways to grapple as a bonus action (like with the feat Tavern Brawler and the maneuver Grappling Strike), but I was wondering if there was a way to grapple as a bonus action without having to attack the target beforehand. Is there any way to accomplish this?

The main intention would be to catch someone off guard with an action that isn't an attack and then grapple them in the same turn. While I don't know exactly when this will be relevant, I believe the circumstance I am looking for will be near the end of the campaign. The campaign will be up to level 20 as well.

I am interested in all ways that this could be done, but for my specific situation I would like to remain mostly a fighter, as I want some of the higher level Battle Master traits (mainly Relentless).

Answer 1

Bigby's Grasping Hand

The spell Bigby's hand says:

When you cast the spell and as a bonus action on your subsequent turns, you can move the hand up to 60 feet and then cause one of the following effects with it. [...]

Grasping Hand. The hand attempts to grapple a Huge or smaller creature within 5 feet of it. You use the hand’s Strength score to resolve the grapple. If the target is Medium or smaller, you have advantage on the check. it. [..., emhasis added]

In subsequent rounds after casting, this allows you to make a grapple check as a bonus action without having made a separate attack first.

This does exactly what you ask for, but will require a rather big investment in a multiclassing to a class that can cast Bigby's hand, such as Wizard or Artificer. What are other alternatives?

Drake Companion

If you want to effect grappling as a bonus action without you yourself attacking first, and without help by other PCs, you could take a dip in Ranger (Drakewarden) (Fitzban's Treasury of Dragons, p. 15). At third level you get to summon a Drake Companion who can help you with grappling as a bonus action (although it would be the companion who grapples, not you):

the only action it takes on its turn is the Dodge action, unless you take a bonus action on your turn to command it to take another action. That action can be one in its stat block or some other action

As the drakes action can be some other action not in its stat block, it should be able to grapple instead of dealing damage with its Attack action, which is one of the standard actions available.

The same tactic would work by taking a two-level dip in Artificer, with a Homunculus Servant, as in Raxy's answer.

Pure Fighter

For a pure fighter, I am not aware of any feat or subclass feature that would allow you to do this. The Battlemaster has a few maneuvers that allow grappling as a bonus action (Grappling Strike, and Restraining Strike), but both of them require an attack first. The Eldritch Knight's spells only go up to level 4 (so not even allowing you to cast the 5th level Bigby's hand).

Answer 2

[This would not require an Action / Bonus Action to perform, but...] you could always command an allied summoned creature (e.g. Giant Constrictor Snake, Crocodile, Giant Crab) to perform an attack with the Grappled condition attached to it, via a spell like Conjure Animals. There are some creatures that require Bonus Actions to command (e.g. the 'Homunculus Servant' from the Artificer Infusion of the same name), that could possibly be utilized if you wish to specifically utilize your Bonus Action for this purpose.

In combat, the homunculus shares your initiative count, but it takes its turn immediately after yours. It can move and use its reaction on its own, but the only action it takes on its turn is the Dodge action, unless you take a bonus action on your turn to command it to take another action. That action can be one in its stat block or some other action. If you are incapacitated, the homunculus can take any action of its choice, not just Dodge.

Per the rules for Grappling itself, it's a replacement for a single attack as part of an Attack action. This wouldn't apply for attacks delivered as part of a Bonus Action (e.g. for the Unarmed Strikes of a Monk's Flurry of Blows).

Grappling

When you want to grab a creature or wrestle with it, you can use the Attack action to make a special melee attack, a grapple. If you’re able to make multiple attacks with the Attack action, this attack replaces one of them.

The target of your grapple must be no more than one size larger than you and must be within your reach. Using at least one free hand, you try to seize the target by making a grapple check instead of an attack roll: a Strength (Athletics) check contested by the target’s Strength (Athletics) or Dexterity (Acrobatics) check (the target chooses the ability to use). If you succeed, you subject the target to the grappled condition (see Conditions ). The condition specifies the things that end it, and you can release the target whenever you like (no action required).

Answer 3

You say:

The main goal is that I want to use my action on something that is not an attack and still grapple someone in the same turn.

While not a Bonus Action the Fighter's 2nd level Action Surge gives you a second action in your turn, letting you do one Action to catch them unaware, and then grapple with a second Action.

Alternatively, switching the problem round, multiclassing three levels of Rogue could give you the Thief's Fast Hands ability to "use the bonus action granted by your Cunning Action to … take the Use an Object action" first and then grapple with your Action after that.

My favourite narrative approach would be to take your glove off and challenge them to a dual, making an improvised weapon attack with it, triggering the grapple from Tavern Brawler or Grappling Strike. You can also do this with Holy Water, splash it on them in a mock blessing "treating the holy water as an improvised weapon" (PHB p. 151), and assuming they are not fiend or undead they will be unharmed.

For completeness, if you take three levels of Berserker Barbarian, and can obtain a Hook weapon like the one the Pirate Bosun wields in the Ghosts of Saltmarsh book, when you Frenzy you can attack with the Hook as a bonus action (and if you hit "the target is grappled (escape DC 13)") without taking the Attack action first. This would also work if you were wild shaped into a creature that can grapple with the Frenzy bonus action attack.