That would be a defenceman, though, wouldn't it? Anyway, I'm game for a discussion about the origins of the game we now call hockey, but that would be topic for another thread.... Well, yes. What I mean is someone who would be described as a "skater" later becoming someone described as a "goaltender." If the switch is on a permanent basis, then all examples will have been a skater at some point in their careers, and a goalie at a later point.
Sure, we could start another thread but I think your on an interesting track here, the Origins of Goaltending, when did it become a designated position. Asking the question what Goaltenders Started as Skaters as good a place as any start that the discussion. Gerry Cheevers as I mentioned is the only modern era Goaltender who Im aware of that not only did have ambitions to play out and did so at a high level (granted experimentally) while at the same time being an elite puckstopper.
We all know the old stories of how the littlest kid, fattest, worst skater or whatever gets assigned to playing goal, never playing out, and in some cases going on to professional & HHOF careers. Many as well do start out playing forward or defense and do so right through Pee Wee, donning the pads at Minor Bantam or even Bantam. Thereafter, if they dont make it to Major Junior, College, University or the Pro's.
I dont know of any that then stopped playing goal, took up playing Wing or whatever in an attempt to make it as a skater with the exception of Cheevers who clearly must have played & developed his forward skills before taking up Goaltending, perhaps simultaneously. Would be very very unusual.... I know plenty however, myself included, who always when playing shinny as a kid or later in a Beer League after hanging up the pads played forward. No interest in returning to the crease. Others however, playing rec hockey as goalies from Bantam into their 70's.
Fact is, being a strong skater is or perhaps I should say "was" an absolute prerequisite during the Standup Era, and was a big advantage previously during the Acrobatic/Flopper Era's as well, and most certainly would have been during the early game when Goalies were not aloud to leave their feet. Todays BF Goalies however, totally different animal. While some of them are good skaters (Smith in Phoenix for eg) a great many are not, incapable of playing the puck properly beyond their own crease.
Just through natural evolution, people playing on Long Pond or wherever, they may or may not have assigned someone to cover the net, it was basically hodgepodge shinny hockey, couldve been 7 aside, 10, 20 players. Where & when I grew up playing shinny, we never bothered with goalies at all. It was just a job to make it to the goal at all, deke through 10-15 + players, passes etc, usually one guy hanging right back there playing semi goal/defence if & when you got that far. So sure, way back when, when Goalies couldnt drop, when there was more of a fraternity within the game pre-professional, a game played by gentleman students, I could very easily envision skaters, Defenseman in particular, perhaps a spare all exchanging the role of goalie game in game out. If one excelled & enjoyed it stayed put in the net.
Back when Goalies had to serve their own penalties, how do you suppose Red Horner & King Clancy of the Leafs, who both had to "play goal" whilst their goalie was in the Box faired? How did they go about stopping the puck? Its not hard to imagine. Weve all seen situations where in the dying minutes of a game, a goalie gets pulled for an extra attacker, next thing you know however the guys with the lead are in deep on the attack, Orr or whomever trying to play Goal. So sure. Very early in the game, maybe a weak skater or someone without skates at all, go stand there in the net. Stop the puck.
As for the last part there Iain, again, I know of no Goaltenders who gave up the pads to play Forward or Defense nor even vice-versa over the past 100yrs of hockey history. None. Zero. So if youd like to re-frame this thread to "Origins of Goaltending 1800-1900". No problemo. Happy to change the thread title, potentially very interesting discussion. So far, who we have here that most anyone can even maybe begin to relate to is Percy LeSueur, one of hockeys earliest innovators & author of the book How to Play Hockey. He designed the Gauntlet Goalie Glove, re-designed the nets used & so on. A unique & interesting individual who contributed much to the games early development. But the farther back we go, rather light on verifiable proof of just about everything & anything. Totally different situation. So no. Your not going to find what your looking for over the past 75yrs. No individual that I am aware of (and Im not the last word on it, but good luck finding anyone) fits your criteria.