Is there a series after the Percy Jackson series?

Yes, there are two series that follow the Percy Jackson series by Rick Riordan. They are:

1. The Heroes of Olympus series (five books):

1. The Lost Hero

2. The Son of Neptune

3. The Mark of Athena

4. The House of Hades

5. The Blood of Olympus

2. The Trials of Apollo series (five books):

1. The Hidden Oracle

2. The Dark Prophecy

3. The Burning Maze

4. The Tyrant's Tomb

5. The Tower of Nero