Buffer/Debuffer, someone who concentrates on support, but not healing. Haste, Slow, Poison, Stun, etc.

Someone who has to perform several actions before dealing mega damage. Either building a rage meter, jumping off screen, or what have you.

There are more specific sub-classes depending on how deep down the rabbit hole you're willing to go. There's evasion based tanks(ninja?), I believe Final Fantasy 11 had one of those. Tanks that want to take damage(Krieg from Borderlands 2). Healers that focus on negating damage instead of healing it.

Can't you just make up stuff to your heart's content? Here's three variations on each and something that's neither melee or ranged:

Melee:
Mirror Tank: Low Health, High Defense, reflects attacks back at attacker, duplicating their damage.
Sponge Tank: High Health, defense increases as they absorb attacks with a medium length cooldown before it drops, allowing them to escalate during a battle from lower tier troops to higher ones, medium damage
Pacifist Tank: High Health and Def, creates buff those in range
Mob Rogue: low health, low damage, progressively creates duplicates of self or enthralls minion mobs to attack target en masse for higher damage
Glacier Rogue, medium health, high damage, super low mobility, just needs to reach bad guys to take them down
Summoner Rogue, low health, low damage, summons one of a few different creatures to deal with enemies, long summon times, creatures do not stay summoned long
Helpful Warrior: all around in health and damage, but must split time with healing
Dark Warrior: all around in health and damage, can also spellcast, but it costs health
Selective Warrior: all around in health and damage, but weak to trollish weapons and magics and strong against eleven weapons and magics.

Ranged

Hulk Mage: medium health, high range, low damage that increases when damage is taken
Proxy Mage: low health, variable range, uses teammates as anchors/channels for attacks
Remote Mage: no health, extreme range, can use map for targeting attacks
Rogue Priest: low health, low range, high mobility to get in and heal and get out
Priest Priest: low health, low range, empowers the healing abilities of other nearby priets
Anchor Priest: low health, no range, places healing markers on ground that help teammates
Grind Summoner: Summoner brings enemies that drop beneficial items
Status Summoner: Minions change based on what status effects Summoner is under
Dupe Summoner: Summoner creates allied duplicate of target

Non-Attack
Recon: medium defense, high mobility, low health, additional detection abilities
Transport: High mobility, high health, low defense, can carry others with them
Peddler: low defense, low health, low mobility, extremely large inventory
Questgiver: low defense, low health, low mobility, increased simultaneous quests, gives XP bonus to party and allows additional party member (themselves)

And this is just a couple things, to say nothing of things like area of effect, damage over time, other status effects, and such further potentially diversifying every potential playtype, in addition to hybridization and the addition of new mechanics adding further differentiation.

Two tricks for making roles feel unique:

First, imagine the archetype in a movie/anime/comic book. Imagine some establishing scenes, some footage of the character establishing what a powerful wizard, or sneaky rogue, or whatever they are. It might be asking a guard for a light and then knocking them out. It might be a crowd of foes surrounding the character then all being thrown away in a giant circle. Design around those scenes: what powers should the roles have, what sort of encounters does the game need to highlight those powers.

Second, come up with a set of fairly generic scenarios. The hero pushes out the underbrush and onto the top of a cliff. Below he spots the enemy camp. Or the hero gets into an argument with a giant in a bar. Or the hero is fighting some soldiers while archers rain arrows down at him from the battlements. Imagine playing each class, how would you react? Shrug off the arrows and finish the immediate fight? Run up the walls of the battlement to dispatch the archers? Retreat and try another approach? Ideally you want each class to have different emotions and strategies in each scenario. Maybe a tight ambush is light hearted fun for a berzerker with all the enemies in close range of his special attacks, but heart pounding for a wizard who's desperately looking for an escape path so he can fight from a distance on his terms. If two roles keep playing the same, figure out different strategies for them. Add or remove skills so one has better options or one no longer has the option they preferred taking.