It all depends on your opinion, because their personalities and specialties vary
According to the book Secrets of the Clans, ThunderClan's original (first) medicine cat was Cloudspots.
Featherwhisker was ThunderClan's medicine cat before Spottedleaf. He was also Spottedleaf's mentor.
Yes, he was ThunderClan deputy to Bluestar between Redtail and Tigerstar.
A she-cat named Daisy, (who lived on a twoleg farm), and her kits Berry, Mouse, and Hazel, (later renamed Berrykit, Mousekit, and Hazelkit), were taken to ThunderClan. They later became Berrynose, Mousewhisker and Hazeltail, ThunderClan warriors.
He said that because he was Stonefur's father and Bluestar was his mother. So he believed no ThunderClan warrior should harm Stonefur as he was their leaders kit. As well as Mistyfoot. Stonefur was half THunderclan. He believed that since the were kin, He shouldn't be harmed.
By Sunrise, the oldest cat in ThunderClan is Mousefur (I THINK). Hang on, lemme look, yes it is Mousefur, 'cause she's older than Longtail. And they are the only two elders in ThunderClan in Sunrise.
The ThunderClan Medicine cat.
Cinderpelt
From Thunderclan: Spottedleaf&Bluestar Riverclan: Silverstream Shadowclan: Yellowfang Windclan: Onewhisker
No, Featherwhisker is medicine cat before Spottedleaf
Dapplepelt is not from ThunderClan. She is a RiverClan warrior in the Warriors book series by Erin Hunter.
She was Thunderclan's medicine cat until a badger had killed her.