Despite monolith being out for some time I still feel hesitant to say that this tier list is "completed" so to speak. I think that a lot of heroes have untapped potential or have yet to have counterplay developed to them. To that end a tier list will always be a work in progress, and once again this is mostly my opinion so take it how you may.

Tier List

Top Tier

Greystone -

High damage output paired with innate tankiness and a second life make Greystone extremely difficult to deal with.

Howitzer -

Excellent damage combined with high utility spells and amazing area control/denial.

Sevarog -

Strong damage output with amazing pick potential and high health pool with Siphon stacks.

Steel -

Extremely strong ultimate that can destroy enemy carries. Force shield is incredibly useful in standoff situations.

Great Tier

Murdock -

In-kit armor shred and a global ultimate give Murdock strong presence in the mid-game.

Twinblast -

Best attack speed scaling of any ranger gives Twinblast extremely high damage output late game.

Gadget -

Strong poke and team utility. Has access to good cards because Order/Intellect affinities.

Dekker -

Brings a lot of crowd control to a team as well as an ultimate that combo's with more than half the cast in some way.

Rampage -

His rock is probably the strongest CC in the game. Performs well in jungle, offlane, or support.

Narbash -

Thunk is incredibly fast and Narbash has the only in-kit healing. Has good peeling potential with his speed up and ultimate.

Feng Mao -

Has strong chase and dueling potential, and his kit offers a little bit of everything.

Khaimera -

Amazing chase and pick potential, but doesn't offer much in teamfights or if he gets behind.

Good Tier

Grux -

Offers solid damage and some CC, but may struggle to find good engages.

Gideon -

Small AoE poke and his ultimate requires him to be close to the opponent. Has high maneuverability with torn space.

Muriel -

Offers strong global pressure with her ult but doesn't have any reliable hard CC in her kit.

Kallari -

Potentially strong pick but relies on getting ahead and may struggle in teamfights.

Grim -

Lower overall damage output than Murdock or Twin, but can still succeed with a strong support.

Average Tier

Countess -

Damage output is still a bit on the low end, but can do amazing if she snowballs.

Fey -

Her spells require her to stand still and her damage output is lower than other mages. Offers good CC.

Crunch -

High damage output but doesn't have a reliable gap closer. May struggle with mana.

Lt. Belica -

Low damage scalings and doesn't have a strong poke tool like other mages. Her ultimate is situationally amazing however.

Kwang -

His RMB gives him a ton of armor and he brings strong burst damage but doesn't do as well as other fighters.

Below Average Tier

Riktor -

Landing hooks can be difficult with the updated movespeed and he is heavily punished for missing abilties.

Sparrow -

No form of self peel whatsoever. Her strongest asset can't be utilized very well in the current meta.

Bad Tier

Iggy -

Suffers from many problems, has low damage output and is squishy. His primary ability gives the enemy CP for essentially free.