Taking a second class somewhere along the game can be very beneficial in creating a powerful character. However, it needs to be done properly, and you need to choose a proper class that fits your main class.
Since playing as a Monk can be quite interesting, we will review which classes are best for multiclassing with a Monk and which classes you should take to have an interesting game.
Exceptionally Good Multiclass Options for a Monk
Monk & Rogue
For everyone who has ever wanted to be a ninja in D&D, choosing a Rogue for multiclass is the best choice. It’s also a class that is best for multiclassing with a Monk.
Both Monk and Rogue heavily rely on Dexterity, which makes this combination a natural fit. They are also similar in combat since both classes usually dash in to attack and then leap back to avoid damage.
First, a Rogue is a great option for many classes because of its early-level features.
Expertise will allow you to double the proficiency bonus for two skills, while stealth is the most obvious skill to improve. However, you might also want to consider Athletics for grappling.
You will also gain a Sneak Attack for one level, which will add an extra 1d6 damage to your attack in certain situations.
On the other hand, note that it won’t work with Unarmed Strike, so you should always have a dagger or some other Monk weapon.
Dipping one level further with Rogue will give you the Cunning Action, which lets you dash or disengage as a bonus action.
A nice thing about Rogues is that they can do some actions that would usually require spending points.
Monk & Ranger
Another great combination is Monk and Ranger, which gives you access to Fighting Style, Spellcasting, and a Hunter ability.
Also, both classes share Wisdom and Dexterity as their primary abilities, which makes multicasting much easier and more efficient.
Note that one level into Ranger will give you Favored Enemy. It is useful because it gives you the advantage of checks to track and recall information about any creature.
Also, you will be able to choose Favored Terrain which will give you certain advantages in certain environments.
Further down the road, a second level will give you access to Spellcasting. Note that the first-level spell you will get is Hunter’s Mark, which adds extra 1d6 damage when you attack a single target.
If you combine it with Fury of Blows, you will deal increased damage to multiple attacks in a turn.
If you choose Fighting Style, Duel would be the best choice for this multiclass.
At level three, you will get to choose the Ranger Archetype, and the best option would be Hunter Archetype. It will give you some nice abilities, such as Hunter’s Prey and Defensive Tactics.
Other Great Options To Consider
Rogue and Ranger go exceptionally well with Monk as the main class. However, if you want to take some other class as secondary, these options also work quite well.
Monk & Cleric
Both Monk and Cleric share Wisdom, which in this case can power up some of the Monk’s features, like Unarmored Defense.
You might also consider building a Monk healer, which can be quite a powerful character.
Note that the spellcasting of a Cleric makes great use of Monk’s high Wisdom score. All of the Cleric spells that you get at early levels work well with Monk, especially if you are aiming at creating a more peaceful, pacifistic character.
In that case, some great choices would be Toll the Dead and Shield of Faith. The Command can also be very useful in some situations.
A good thing is that only one level into Cleric will give you a Domain. Depending on the Domain you choose, you will get some great first-level abilities. The Light and Tempest both provide some great abilities.
Another good option would be The Peace Domain. The Emboldening Bond feature lets your party have +1d4 damage on any attack as long as they are in the 30-foot radius.
At the second level as a Piece Domain Cleric, you will get Balm of Piece. It allows you to restore a number of hit points equal to 2d6 + your Wisdom when you are within 5 feet from any party member.
Monk & Druid
Druid uses its power to invoke the forces of nature and protect its home. As Monks and Druids both have Wisdom as primary ability, this multiclass can work quite well.
If you choose Druid, your Monk will get spellcasting, healing magic, and transformation abilities.
Note that with Druid as your second class, you get access to some very useful spells, such as Healing Word, Cure Wounds, Faerie Fire, and Charm Person. You will also get animal-related spells, such as Speak with Animals.
Wild Shape is a great thing to consider, but you should check with your DM whether you can replace the damage dice with martial arts dice. Anyway, Wild Shape is very useful for stealth and exploration.
You should only note that Druids have no use for most armor since you can’t wear metal as a Druid.
Monk & Fighter
With the Monk and Fighter combination, you can get both spiritual and physical excellence. You will be able to weave elegantly through the battlefield and do powerful attacks and then leap away before you get hit.
Choosing a Fighter class will give you an Action Surge, and a martial archetype. For a traditional Monk, Dueling is probably the best fit, since it will deal a +2 damage when you have a melee weapon in one hand and the other hand is empty.
Another nice thing is that with this class you will be able to heal yourself using the Second Wind. It restores 1d10 + your fighter level of hit points.
Since you get Flurry of Blows at the second level and an extra attack and the fifth level, Action Surge might not be very useful. However, it will still give you the opportunity to do a bit more damage.
Monk & Artificer
It’s fact that Artificer’s spellcasting doesn’t do much for a Monk. However, if you take a ranged cantrip, it can help shore some of the Monk’s weaknesses, and the Absorb Elements spell fits quite well in this combination.
There are not many benefits at a low level, except a few utility items. Note that almost all effects of the Experimental Elixir are good for a Monk, but the effect will be randomized when you make it.
The Enhanced Weapon is also nice, but note that you will mostly be making unarmed attacks.
At some point, your fists will become as good as other weapons, and if you play as a Human, you can dual-class and take three levels. It can be quite beneficial for a Monk.
Monk & Barbarian
It might seem counterproductive to combine Monk and Barbarian classes since Barbarians rely mostly on strength.
Obviously, Monks can also have a high Strength score, but Dexterity has the added bonus when it comes to boosting your AC.
Note that using Strength when attacking gives this class combination +2 damage when raging, which can be quite good considering how many attacks you make per turn.
Unarmored Defense won’t stack, and in most cases, you won’t have enough hit points to back up Reckless Attack.
On the other hand, if you invest in three levels, a great subclass would be Path of the Totem Warrior. The Bear Totem will significantly boost your defense, and the Eagle Totem will work quite well with mobile characters.
If you choose this multiclass, the ideal races would be Human, Bugbear, and Goblin.
Monk is a very interesting class to play with, and combining it with other classes can make quite a powerful character. However, you will gain the most benefit if you choose Rogue or Ranger as your second class.
Barbarian is the least effective, but it is more effective than Bard or Wizard, and also leads to interesting gameplay.