Does Torpor Orb prevent triggered abilities from commanders entering the battlefield?

Torpor Orb states that creatures entering the battlefield don't cause triggered abilities to trigger. This is a blanket suppression effect that applies to any creature entering the battlefield under any player's control, including commanders entering from the command zone.

Under CR 603.6b and the general rules on triggered abilities, an effect that prevents triggered abilities from triggering stops them before they even go on the stack. The commander's 'enters the battlefield' ability is never placed on the stack at all, so it cannot be responded to or saved in any way.

It doesn't matter whether the commander is entering from the command zone, from exile, from the graveyard, or from anywhere else — Torpor Orb suppresses the trigger regardless of origin (CR 614.1, 603.6b). The only caveat is that Torpor Orb only affects triggered abilities (those beginning with 'when,' 'whenever,' or 'at'); static or activated abilities of the commander are unaffected.

Example: Your opponent controls Torpor Orb and you cast your commander Avenger of Zendikar. When Avenger of Zendikar enters the battlefield, its triggered ability that creates Plant tokens is suppressed by Torpor Orb and never triggers — you get zero Plant tokens.

Note that abilities that trigger because a creature entered but are on a different permanent (e.g., a separate creature's 'whenever another creature enters' ability) are also suppressed by Torpor Orb, as the effect covers all creature ETB triggers, not just those on the entering creature itself.