As of patch 2.0.6. an alternative avatar named Helga Hammerstorm can be acquired.
And then at patch 2.6.21 a new heroine—not an alternative avatar—got added in the roster... named Solstice. This is her◊, with and without armor.
Bramble is a Strength hero and was released before Solstice, and is technically a female.
After the End: According to the Excuse Plot outlined in the "Savage" games, modern day civilization had it's downfall ages ago and in the far future humanity is once again on it's rise to power but is no longer the single dominant species on the planet as the beasts of the land had evolved and become intelligent. Or, rather, it was going for dominance until the Hellbourne started their onslaught at which point it became a battle for survival and an alliance of convenience with the Beast Horde was formed to fight the daemons.
Jesse Cox of OMFGcatavoices "Spiriticus", a (male) alternate skin for Nymphora.
Captain Ersatz: The game itself is a replication of DotA, updated to a much more flexible engine and with lots of online multiplayer convenience. Those days it's split off much more from DotA and has established its own metagame and many different heroes.
Crosshair Aware: Scout's Marksman Shot and Flint Beastwood's Money Shot will put a bullseye above his target while he's charging the ability.
Damn You, Muscle Memory: Try pressing Alt+QQ in HoN. Then switch to DotA and do it again. Plus, spells in HoN all have QWER as hotkeys, rather than varying from hero to hero. So even if your favorite DotA hero happens to be in HoN as well, chances are the initial hotkey confusion will throw you off.
Rather, if you're switching from HoN back to DotA. For those coming from the mod, standardised hotkeys are a godsend. Of course, you can change the bindings in-game, so its pretty much averted here.
Thankfully, Dota 2 uses the QWER hotkeys as the standard, so it's not so much an issue anymore.
Dark Fantasy: A setting where the Legions of Hell is marching towards humanity and beastmen? Check. Weapons at the store that are mostly created by the forces of Hell? Check. Being forced to kill your own men? Definitely a Dark Fantasy setting.
The game itself is Dark and Edgy in general, unlike the lighthearted League of Legends. The heroes will be more than glad to kill their own if they need to and the game has the feeling of a Dark Fantasy.
Bladeknight5: Probably the biggest thing for me when I started playing Ho N, was that I got distracted by all the shiny graphics, I'd be like "Woah that spell is really - CRAP I'm dead." and my team would be like, "Why'd you sit there?" and I would be like, "Ummm... Lag?" 
Dual Wielding: Blacksmith with his dual hammers, the Dark Lady with two katars, Madman with a pair of claws, and Swiftblade with his dual katanas. Flint Beastwood uses dual shotguns.
You can combine Firebrand, Icebrand, and Lightbrand with each other into one item. This only counts to the trope if you have two of the three. Having all three will combine them into a single sword called the Dawnbringer.
Enemy Mine: When the Hellbourne threw down, the Human Legion and Beast Horde ended their war and joined forces to fight against the demons.
Magebane is allowed to help fight against the Hellbourne - if not for the war, the priests of Sol would have burned Magebane at the stake as a heretic.
Also, Prisoner 945 is well... a prisoner from the dungeons of The Legion's capital, who was imprisoned for leading the rebellion of the Titans. He was released to give Legion another hero that will fight for them, with his chains on him still intact; promising him freedom from the chains if he does well in their fight against the Hellbourne.
Evil Chancellor: Pestilence was once a chancellor to Moon Queen before joining the Hellbourne for power.
Expy: Being an update of DotA, a lot of the heroes have DotA counterparts. Some are fairly obvious (Moon Queen ~ Luna Moonfang, Pyromancer ~ Lina Inverse, Soul Reaper ~ Necrolyte, Keeper of the Forest ~ Treant Protector), but others (Plague Rider ~ Lich, Pharaoh ~ Clockwerk Goblin, Pestilence ~ Slardar, Rampage ~ Barathrum, Witch Slayer ~ Lion) are a bit more subtle.
Myrmidon is an expy of the infamous Magikarp from Pokemon
"Myrmidon uses Taunt on newbie." followed by "It's super effective!"
made even funnier when you realize gyarados frequenly used Taunt
The Blood Hunters left the Beast Horde for the Hellbourne, knowing that they'd be able to drink more blood serving the demons.
Corrupted Disciple once was a priest of Sol, before he was, well, corrupted, and joined the Hellbourne to serve their unholy energy instead of Sol's light.
Demented Shaman betrayed the Beast Horde after gaining access to their holiest secrets to join the Hellbourne.
Forsaken Archer, in life, was a woodland huntress. After being raped and killed by a spurned suitor, she was revived by the Hellbourne to carry out her revenge on the men of Newerth.
Hellbringer, a warlock addicted to demon magic, left the Legion to join the Hellbourne and became the most despised man on Newerth.
Maliken, once the grand leader of the Legion, mysteriously vanished one day. Now he leads the Hellbourne to fight against the very Legion he was once part of.
Pestilence once served the Moon Queen, but after realizing that he could never become ruler, he left the Moon Warriors for the Hellbourne and a chance at power.
Myrmidon was in the Legion for a few months, but once someone found out he was a kind of water daemon, he joined the Hellbourne.
Prophet was a Legion hero for a while, but once the dire consequences of his pacts were realized, he defected to the Hellbourne.
Glacius had this happen to him twice. Initially, Glacius was a Hellbourne hero, but some time later he was changed to a Legion hero with a different lore. Some time afterwards, he became a Hellbourne hero again, with his old lore.
Fake Difficulty: A complaint brought up fairly often about the game is that the shop grid layout and user interface are unnecessarily complicated.
The shop UI was remade to be more user friendly, but some think that it was made less user friendly, although those complaints died within a week or two of it's introduction when people got over the whole They Changed It, Now It Sucks thing.
"Others say he is a man, just a man, but driven mad by the endless carnage he has witnessed."
Gods Need Prayer Badly: In the world of Newerth, gods do exist, but their power depends largely on faith. Currently Sol is the most worshiped god and is omnipotent, while the other gods, having been mostly forgotten, are about as strong as the heroes. While Amun-Ra isn't an evil god, he was able to be summoned by the Hellbourne as a corrupt version of his true form because of this.
Green Thumb: Keeper of the Forest, Deadwood, Nymphora, and Bramble.
Subverted by Deadwood really; ripping trees out of the ground as weapons? Stampeding through forests and taking their lifeforce to speed himself up?
Runes of the Blight, in its unused info, saps the life force of a tree to restore health. It's supposedly "evil", but it's so useful they don't mind it.
Good Is Not Nice: Legion might be the good guys but they sure aren't the nice ones.
Instant-Win Condition: World Tree/Sacrifical Pit destroyed? Game over, no matter how many enemy heroes you and/or your team shredded.
Invisibility: Many sources. Scout can Vanish, Night Hound has Invisibility, Keeper of the Forest can Camouflage himself or his teammates, Madman can Stalk in the shadows, Fayde can activate Reflection, Revenant can use Essence Shroud on one or more allies, and the item Assassin's Shroud will cloak the user when activated. Grinex can go invisible at least 3 times in succession.
Item Crafting: Maintained from DotA. You can combine base items into more-powerful items using recipes. There are well over five dozen recipes.
It's Up to You: Solo mid gankers generally control the game up until lategame, where they pass the reins to the team's carry who will seal the victory almost singlehandedly.
In the mean time, supports will place wards around the map and help out their teammates in whatever ways they can all game.
Light Is Not Good: The item Mock of Brilliance releases burning light that damages enemies near the carrier.
Light 'em Up: Jeraziah's Inner Light. Also Moon Queen's Moon Beam and Moon Finale spells.
Lightning Bruiser: Armadon, Pestilence, and Rampage, three Strength heroes that are rather agile.
Linear Warriors, Quadratic Wizards: Inverted. Nukers (wizards) are very powerful from early to mid, quickly dropping off during mid- and late-game. Carries (warriors) tend to be very weak early game, eventually becoming a monster late game, killing heroes in 2-3 hits.
Loads and Loads of Characters: 120 as of this edit. About 40 or so of them were ported directly from Dota All Stars, but since then S2 Games has been developing their own heroes on a regular basis for 3 years, not to mention some of the ported heroes received major changes.
Luck-Based Mission: Casting Blacksmith's Fireball. Will you do as little as 275 damage... or as much as 1100?
Standard Status Effects: This game has a lot of possible status effects, so naturally a few of them match up. Slither's skills cause poison, Pyromancer's Fervor causes burning, a number of heroes have ways of silencing, Blood Hunter's Blood Craze is essentially berserk, Glacius's Ice Imprisonment freezes, Maliken's Possession fears, and there are quite a few slows and stuns in this game.
Decovery is the theme built around Lord Salforis's skills. He can briefly reduce all healing applied by half, steal passive HP regeneration around him, and make a target completely unaffected by any source of health.
Suffers Newbies Poorly: Most of the community actively push new players away. In this game, you getting killed does not just hurt you - it helps your enemy, as they make progress towards leveling up by killing you, so a newbie that dies more than average can actually be a net loss to the team. Experienced players know this, and will vote-kick, or cuss out, newbies, to make them leave. Overall, the incentives are structured such that newbies are a liability and experienced players seek to push any on their team out of the match, either by harassment or simple vote-kick.
The announcer and the game even mocks the player for poor playing skills ranging from saying "TOO BAD" for whiffed skillshots. To Unreal Tournament style killquotes. Heroes of Newerth is a ruthless game and it's setting reflects upon it.
Maliken's Possession turns him into a hulking demon with a ranged splash attack. When he turns into one, enemies around him literally cower and panic.
Hammerstorm can summon up his Brute Strength and more than his damage.
War Beast undergoes a Metamorphosis making him really goddamn fast.
Madman can go Berserk and totally flip out on an unfortunate victim. With Staff of the Master, if he gets killed, he'll die 5 seconds later.
Berzerker can unleash Carnage, making him hit [[Clerks like a truck]], with the endurance of one. He takes more damage during it, though.
Salomon can turn into an Avatar of Revenge, gaining a second health bar and an all new set of abilities.
Super Speed: While War Beast is transformed via Metamorphosis, he gains max movespeed and can't be slowed at all.
Blitz is emphasized on speed. In fact, he can go beyond the normal movespeed limit.
Summon Magic: The item Puzzlebox, plus a lot of hero skills, ranging from Forsaken Archer's Call of the Damned, Hellbringer's Summon Malphas, War Beast's Summon Hellhounds, and Wildsoul's Summon Booboo.
Super Strength: As in "super lots-of-Strength-points". Devourer will add any enemy heroes that dies within him to his bulk, gaining a point of Strength each time. Late game he can easily reach over 200 Strength, which is basically saying "HAHAHA now i kill you good". Up to Eleven if you're playing Mid Wars.
In a similar vein, it's not uncommon to see a Strength build Shadowblade with over 4k HP.
Teleport Spam: Accompanied by sword slashes when Swiftblade triggers his Swift Slashes.
This is called 'snowballing' and it is only true on team level. Individual heroes that perform well during the early game are useless 30 minutes later and vice versa. However, if there is just one bad player on your team who keeps dying, the game is lost no matter how good the rest of your team is.