Joe and Ethel Turp is not available due to legal entanglements.The photo of "Lady of Burlesque" (1943-UA) tells me that Stephanie Bachelor's career wasn't 'entirely' restricted to Republic (like I thought). But mostly so. I don't think there are too many B-players whose leading man/lady roles were 100% exclusive to a single studio, but there are a few, and a few others come close. Jinx Falkenburg at Columbia comes to mind. Did Linda Stirling ever do any films outside Republic, other than a few bit parts? I think Eleanor Whitney, who starred in a number of breezy B-musical-comedies at Paramount in the 1930s, never strayed from her home studio. I also associate Louise Campbell with Paramount, although she might have eventually gravitated to poverty-row. Did Sydney Fox ever have a leading-lady role outside of Universal? Not sure, but I can't think of one.
On the flip side of the coin, what about B-stars who might have managed to star in at least one film at just about EVERY studio? The closest leading-lady I can think of is Jean Parker. She was with MGM at first, culminating in things like "Sequoia" (1934), before eventually fleeing from Louis Mayer's greasy clutches. During that time, she did some RKO's, like the neat rural melodrama "Two Alone" (1934) and the Fred Stone comedy "Farmer in the Dell" (1936), the latter film strangely absent from TCM, even though I saw it on TNT thirty years ago. At Paramount, Parker was leading-lady to George Raft in "Limehouse Blues" (1934) and to Fred MacMurray in "The Texas Rangers" (1936). She starred in "Life Begins with Love" (1937) for Columbia. Lots of Republics, twice opposite Phil Regan in 1939, and later headlining "The Girl from Alaska" (1942). Many Monogrammers too, from "Romance of the Limberlost" (1938) to those two Kitty O'Day comedy-mysteries in the mid-1940s. Parker also made tons of those Pine-Thomas titles at Paramount... "Wrecking Crew" (1942), "Alaska Highway" (1943), etc. She was probably their most prolific leading-lady. Parker was also in PRC's "Bluebeard" (1944). Not much over at Fox, although she was in "Caravan" (1934), that odd but enjoyable gypsy-musical confection, and (if I recall correctly), she wound up winning the leading-man, Charles Boyer, over the main star, Loretta Young. The only studio I don't think Parker worked under is Warner Bros.
As for B-level leading men who seemed to work at every studio, I think William Gargan must be in the top spot, or near it. Early on, he headlined RKO's "Headline Shooter" (1933), and was also lead in a few Columbia's like "The Line-Up" (1934), which I've always wanted to see, and "Alibi For Murder" (1936), the latter available thru Sony Archives. At Warners, Gargan was lead in several of their minor, mid-1930s B's, like the funny "A Night at the Ritz" (1935), which I always liked. He starred in the early Republic "Navy Born" (1936), a common pd title. He did a few scattered Paramounts, like the loopy comedy-mystery "She Asked for It" (1937). Gargan starred in a ton of Universal B's, from "Reported Missing" (1936) to "The House of Fear" (1939) and "Song of the Sarong" (1945). Didn't do too much at MGM, but he was one of the title characters in their "Joe and Ethel Turp Call on the President" (1939), which I haven't seen in eons. At Columbia again, he took over the Ellery Queen role from Ralph Bellamy in that early-1940s series of films. Like Jean Parker, he was in a slew of those Pine-Thomas films at Paramount, like "Midnight Manhunt" (1945) and "Dynamite" (1949), and such. He even finally made it to Fox studios for "Behind Green Lights" (1946), and producer Sol Wurtzel's "Rendezvous 24" (1946). Never seen those. I think Gargan covered just about every base, other than dipping down to Monogram and PRC (that I know of).
Hmm, anyone think of any other B-stars that managed to work at just about every studio, more than either Jean Parker or William Gargan? I thought maybe Edward Norris, but although he zipped around just about as much, he was often limited to 'second leads' and down-the-cast roles.