Some of them.
Dungeons & Dragons Online is celebrating sixteen years this month, and nothing says birthdays quite like presents. In addition to the usual annual celebrations, Standing Stone Games announced that players can look forward to multiple races and classes becoming permanently free for everyone.
The list includes gnome, half-elf, half-orc, drow, wood-elf, dragonborn, and tiefling. The list of classes being made free is druid, monk, and warlock. Players who already owned one of these races or classes will receive a Greater Elixer of Discovery for each that they owned.
Speak with Jubilee the Discoverer on the bottom floor of the Eberron Hall of Heroes to get one Bound to Account Greater Elixir of Discovery for each feature you had previously purchased. You may only claim each feature’s Elixir once in total (across all characters and servers), so please use caution if you play on multiple servers.
More details on the official website.