CreateEmptyList

This node does exactly one thing: it hands you an empty Python list. No inputs, no parameters, no settings - drag it on the canvas, run, and the list output is []. It's the kind of node you'd be embarrassed to defend to someone who hasn't spent an afternoon fighting a ComfyUI loop, and the kind you immediately understand once you have.

The reason it exists is accumulation. ComfyUI's loop story (the PixNodes For Loop Start/End pair, or any of the while-loop variants) is stateful: you feed values into the start, the loop body transforms them, and the end feeds them back for the next iteration. If you want to collect every iteration's output into one growing list - say, each loop pass produces a prompt or a frame you want bundled at the end - you need a list that starts somewhere. Pix_CreateEmptyList is that starting point: its output plugs into the loop's initial_value slot, the loop body appends to it each pass, and when the loop finishes you've got the accumulated list.

That's the whole pattern, and the KB's node-plumbing essay calls this exact role out: the "accumulator start" is one of the genuinely recurring shapes in the plumbing layer, the invisible 70% of every workflow that touches no pixels. This node is a one-liner implementation of it.

The single output is typed as a wildcard *, which sounds weird but is deliberate - the list is empty, so it has no element type yet. ComfyUI lets the downstream connection decide what kind of list it becomes. That's also the one thing that can trip you up: because the type is unresolved until connected, an unconnected Pix_CreateEmptyList is just a dangling [] and ComfyUI may skip it. Wire it somewhere real.

Install is the usual PixNodes deal - ComfyUI Manager, search PixNodes, install, restart - or by hand:

cd ComfyUI/custom_nodes
git clone https://github.com/pixixai/Comfyui-PixNodes
cd Comfyui-PixNodes
pip install -r requirements.txt

then restart ComfyUI. Dependencies are just openai and Requests; there's no model or heavy library involved, so this node works on any install that has the pack at all.

Honest take: you will not use this node often, and you'll forget it exists between uses. But the day you're building a loop that needs to collect results, you'll search "create empty list", find this, and save yourself the subreddit question. There are similar nodes in other packs (rgthree and the Easy-Use lineage do their own variants), but if you're already in the PixNodes ecosystem for its loops, this is the one that matches.