**Brightwing:** Gets colorful shadow effects if Blink Heal ultimate ability is chosen:

[![Before][1]][1] [![After][2]][2]

**Cho'Gall:** Gets a hammer if Hammer of Twilight ultimate ability is chosen as Cho:

[![Before][3]][3] [![After][4]][4]

**Dehaka:** As OP points out, regenerates an arm if any of ultimate abilities is chosen:

[![Before][5]][5] [![After][6]][6]

**Gazlowe:** Gets disks if Robo-Goblin ultimate ability is chosen:

[![Before][7]][7] [![After][8]][8]

**Varian:** As OP points out, wields different weaponry based on the ultimate ability chosen:

[![Before][9]][9] [![After Taunt](https://i.sstatic.net/IM9j8m.png)](https://i.sstatic.net/IM9j8.png) [![After Colossus Smash](https://i.sstatic.net/XBFpSm.png)](https://i.sstatic.net/XBFpS.png) [![After Twin Blades of Fury](https://i.sstatic.net/8q6lsm.png)](https://i.sstatic.net/8q6ls.png)

Some more info in this [reddit post][13].


  [1]: https://i.sstatic.net/Sz3VZ.png
  [2]: https://i.sstatic.net/1mpua.png
  [3]: https://i.sstatic.net/HKT35.png
  [4]: https://i.sstatic.net/eLVqF.png
  [5]: https://i.sstatic.net/MwYx3.png
  [6]: https://i.sstatic.net/2TZcP.png
  [7]: https://i.sstatic.net/OezNg.png
  [8]: https://i.sstatic.net/RLt6z.png
  [9]: https://i.sstatic.net/9666n.png
  [10]: https://i.sstatic.net/IM9j8.png
  [11]: https://i.sstatic.net/XBFpS.png
  [12]: https://i.sstatic.net/8q6ls.png
  [13]: https://www.reddit.com/r/heroesofthestorm/comments/4ne9zp/i_really_love_that_gazlowes_appearance_changes/