Henchmen are a special character type: they're created by the DM and played by other players. Henchmen are the sort who for which it would be impossible to pass the 1st level of experience alone. Much like how typical men-at-arms can never gain a class level, henchmen can never gain more than one class level without help from more-capable characters.

PCs seek and then hire henchmen, who are owed a half share of treasure (by standard), as well as their equipment and upkeep paid for (but not training). In exchange for this, the henchman has some measure of loyalty to the individual PC (not the party!).

Class restrictions are those most favorable to the PC. So a fighter/assassin could hire non-assassins early on despite the assassin restriction, since fighters don't have that restriction.

The 100 gp per level initial payment also applies to the extra gold to raise the base chance from 25% to 35%, 45%, or 55%. For example, the thresholds for a 2nd level character are 200 gp, 400 gp, 600 gp, 800 gp.¹⁾

A henchman's liege must pay all equipment and upkeep costs. The henchman pays for their own training.

If a character desires to seek henchmen, their player should indicate as much to the DM at least 1 week before the desired session.^Ex

Offer money accepted by a henchman goes out of the game. They retain magic items offered to them. They do not start with any money and must be fully furnished by their employer, with the exclusion of those magic items.

The rules on DMG 35 say that magic arrows are counted in groups of 5, but don't list groupings for other ammunition types. Here they are, extrapolated from their XP value:

Players must play their henchmen as separate characters. Though the DM can veto an action and take control of a henchman, this should not be necessary if there is sportsmanship at the table. But that is about players mishandling henchmen. PCs are welcome to mishandle henchmen all they want (and that might even be great roleplaying at times), but these cases should be handled with a loyalty check.

Remember that henchmen are in a way a roleplaying challenge. Players should challenge themselves to play these characters as separate characters. How does the PC and henchman feel about each other? Maybe they will really strike it up, or maybe they will often differ. Having a PC differ from their henchman in action or opinion on occasion is a hallmark of good play.

All XP earned by a henchman suffers a 50% penalty before it is added to their total.²⁾.

For example, if a henchman is being provided with the standard half share of treasure, they will get that half share of treasure and a full share of combat XP. That number will be totaled, and then the 50% penalty will be applied before the total is recorded. So in this example, the henchman would end up with a quarter of the treasure XP of a PC, and half the combat XP (assuming all treasure shares are equal in value).

See Death for special henchmen rules concerning death.

Once the number of henchmen who will answer the call has been determined, the DM must determine the henchmen's races, classes, and ability scores. The DM may also desire to define personality and appearance, but since these characters are meant to be played strictly by a non-DM player, it is also acceptable to leave that to the player who hires them.

1. Determine race. The DM may wish to set particular percentages based on the location. Otherwise, 80% are human and 20% use the table found on DMG 176. Do not use the multiclass rule from that table; you should use the multiclass rule listed in the henchmen section on DMG 35 (see “Determine class” below).^{3) 4)} It's recommended that you only allow UA races to be available in special cases so as to not end up with a large amount of UA races in the game (especially if you allow henchmen to become PCs if their master is lost or retires).
2. Determine first class. Use the table on DMG 35 (reproduced below). Make sure to read all text in that DMG section (“Classes Of Prospective Henchmen”). If the result is illegal for the race, select the closest approximation (e.g. fighter instead of paladin), or re-roll if there is no approximation (e.g. in the case of rolling magic-user for a dwarf).
3. Determine ability scores.
   1. Roll 3d6 down the line, but for prime requisites of the determined class, add +1 to every die that doesn't roll a 6. ⁵⁾
   2. Modify the results for race.
   3. Determine any additional classes for non-humans as per the text on DMG 35. Do NOT grant ability score bonuses for these additional classes.⁶⁾
   4. Modify the results further as per the table on DMG 100 (multi-class characters receive all bonuses).
4. Determine alignment. DMG 100. Re-roll any alignment which is illegal for the class(es) which have been determined.⁷⁾ Monks have a special alignment chance found on PHB 30 which should be used instead of the standard NPC alignment table.
5. Determine personality. DMG 100-101. Do not roll age, since that will be determined in the usual way. ⁸⁾ Use any combination of the tables on these pages you desire, and freely invent your own quirks. Don't go overboard; remember that the player will be roleplaying this character, and it's best to give them a chance to develop it in an interesting way. Just a sentence or two to spark the imagination is all you need.

The rest of the apparent characteristics (height, weight, age, etc.) can be rolled by the player if the henchman is hired. If the PC convinces a magic-user to expose their spell list, the player can roll for those too.

Aging effects on ability scores are applied as normal. (The scores rolled by the DM are pre-aging.)

When you've composed the list, remember that henchmen trickle in over a 2-8 day period. ⁹⁾ Of course this period may pass during 1:1 time between sessions.

Once the player has been given the full list, allow one in-world week for their character to decide on hiring before you apply a weekly 50% roll for each prospective henchman, failure indicating they depart (or be hired by someone else).^Ex

From DMG 35, for convenience:

Use the rules on DMG 175 to determine levels. Here is the summary:

When generating henchmen for NPCs, henchmen have a base level of master_level / 3, rounding fractions of half or less down (e.g. round to the nearest number).

If the NPC master is 9th level or higher, add levels to that base number equal to master_level / 3, but always rounded down (e.g drop all fractions).