Originally Posted by
Gehco
Trials of Valor Mythic can be solo'd if you have some mobility and damage to boot (Can at least be done as Hunter (because pet), Mage (Because of Blink), Warrior (Because of heroic leap), Druid (Because of Dash), Rogue (Because of sprint) - Bonus if you are a Worgen (Because of Darkflight).
Everything can be solo'd in Siege of Orgrimmar Mythic, some just mean a little more time (Like the first boss) and others mean not too much damage (Like the Klaxxi, they bug if you nuke them).
Everything in Heart of Fear can be solo'd. Nothing prevents you to just rush to through, even the last boss.