Alex Kidd has made several cameo's and has been referred to in several other Sega games. Below is a list of them:
There is a homage to Alex Kidd in Altered Beast, where the names of Alex and Stella, Alex's female companion from the arcade version of Alex Kidd: The Lost Stars, appear on gravestones in the first stage.
Alex's face can be seen hidden in the backdrop of the third level of Kenseiden on the Sega Master System. It is mold in the scenario, on the ground, by a dead end, next to a pit of lava.
Alex appears several times as collectable toys in the Dreamcast game Shenmue, and the Dreamcast/Xbox sequel Shenmue II, the latter marking the first time he ever appeared in a game for a non-Sega console.
Segagaga is a Dreamcast game where you get to take control of Sega to help it win the video game war. At one point in the game, you run into Alex, who tells the player of his tragic story of how he used to be the mascot of Sega and his rivalry with Nintendo's mascot Mario.
He then tells the player of how was demoted in favor of Sonic the Hedgehog as Sega's new poster boy. Now, instead of starring in his own video games, Alex's subdued to working a retail job at one of Sega's shops. This is a sad yet comical look at Alex Kidd's ultimate fate.