Tinker is voiced by Harry S. Robins, who has done numerous voices for Valve's hit First-Person Shooter series, Half-Life. Many of his lines make reference to, if not direct quotations from, the series.
Lich has a particularly specific line when casting Sacrifice:
Omniknight's Ultimate, Guardian Angel is refered to as Hammer Time, due to the fact that you cannot touch someone under it. And he has a hammer.
Nature's Prophet: His original name in DotA was Furion, but this was changed in the transition to DotA 2 due to copyright reasons. However, his actual name (prior to it being redacted) is very rarely used due to being unpopular and Furion is frequently used instead. The game files still refer to him as Furion.
Others know him as Nature's Profit due to his farming abilities.
Disruptor: "Dis Raptor," given his mount of choice.
Spirit Breaker: Space Cow, after the PyrionFlax guide to Spirit Breaker. This later became an Ascended Meme with the Three Spirits patch; Earth Spirit refers to him as a "space cow" in some of his responses.
Witch Doctor: "The Walking Fountain," because of his constant AoE heal and ultimate.
Dark Seer: "Dark Sonic" due to the spikes on his back giving him the appearance of a hedgehog, and his Surge ability allowing him to GO FAST.
Bloodseeker: "Pubseeker", due to his high popularity in public / pickup games. He also goes by the moniker "Bloodcyka" for his popularity among Russians in the low-skill brackets note the curse word "сука" is synonymous with foul-mouthed or uncooperative Russians in the fan community.
He's also sometimes referred to as "Race Car" and "Ferrari Seeker" due to the 6.79 patch which completely removes his speed cap when his Thirst passive is triggered.
Windranger: "Windginger", because she's a redhead. note and because fans didn't like her name being changed from Windrunner
Venomancer: "Bananamancer", due to his old model's curved posture and bright yellow-green color.
Slark: "Fishi", due to his appearance and (as a ganker) inevitable comparison to Riki.
Earth Spirit: "IMB Alance Spirit" or it was after his nerf in 6.80 that name went to...
Ember Spirit: "The New Imba Spirit"
Hey, It's That Voice!: A lot of the voice actors worked on Valve's previous games, so it's not surprising to hear familiar voices.
Screwed by the Lawyers: Many Heroes have had their names changed from their initial iterations since they bear similarities to characters from Blizzard franchises (the main issue coming from the Blizzard-Activision merger making lawsuits a very real possibility):
Brewmaster was previously Pandaren Brewmaster. Due to the Pandarens being a Warcraft race, the "Pandaren" was removed and his design was shifted to resemble the red panda.
Similar to above, the three Spirits (Storm, Ember and Earth) used the Pandaren model in the original War3 Dota, and had their designs changed to more closely resemble humans.
Magnus is referred to as Magnataur in the game files. The Magnataur are a race in the Warcraft universe, so the Magnoceros race was created in its place.
Nature's Prophet had the name "Furion" in Dota 1, being a shortened version of "Malfurion Stormrage," a prominent Warcraft character.
Necrophos was originally known as Necrolyte (and is still referred to as such in the game files).
Outworld Devourer's original name was Obsidian Destroyer, based on a Warcraft 3 unit, so his initial Dota 2 name was Outworld Destroyer. It was very briefly changed to Outworld Demolisher, and then again changed to the current Outworld Devourer. Some fans jokingly refer to him as Ongoing Developer due to this.
Windranger was originally known as Windrunner. The change came due to Windrunner being the surname of a prominent family of heroes in the Warcraft universe.
Wraith King was originally Skeleton King, who was based on the Diablo character King Leoric. The entire Frostivus 2013 event was created around the complete change in his appearance.
Talking to Himself: Despite having well over a hundred different heroes, there are scarcely more than ten or twenty voice actors to give them all voices. While some of these are fairly obvious (Anti-Mage, Beastmaster, Necrophos and Warlock are all voiced by Sam A. Mowry, and sound like the same person at different ages), quite a few are very surprising (Crystal Maiden, Drow Ranger, Enchantress, Mirana, Phantom Assassin, Spectre, and Vengeful Spirit are all voiced by Gin Hammond, and Timbersaw, Bristleback, Skywrath Mage, and Abaddon are all voiced by TJ Ramini).
This can reach its peak when certain Heroes give responses after killing others.