Garthanos
Arcadian Knight
Shepherd druid and glamour bard are from xanathar's guide and artillerist artificer is from eberron: rising from last war. Glamour and artillerist both have a way to hand out a small amount of THP as bonus action repeatedly and shepherd druid can give out LV +5 THP once a short rest as a bonus action to a large area.
Sounds like one went a closer model to Leadership feat. and the others are surgical patches like Rally.