Well that’s a good question. Depending what you mean by Disneyland.
If you mean the park, there’s only one I have evidence for.
On July 8, 1974 a Cast Member named Deborah Stone was working America Sings (an attraction where Innoventions now is today) greeting guests over a microphone and bidding them farewell when they left. As quoted in Mouse Tales: A Behind-The-Ears Look At Disneyland by David Koenig
"At the end of the 24 minute show, there was a 45-second interval after the audience had left the theater in which the stage moved into position to start a new cycle. Somehow, Stone got too close to the passway between the rotating theater wall and the stationary stage wall.A guest in the adjacent theater heard a screamed and turned to see what looked like a child being pulled between the two walls. As soon as the theater stopped moving, he notified operators. The two passing walls had crushed the hostess to death."
It was the poor dear’s first week working at Disneyland, too. At the time, it was a wide spread story. People came from all over the country, as well as parts of Europe to visit and give their condolences to the family of Deborah Gail Stone.
If you mean the Resort, well there’s one I know from Disney California Adventure.
In April of 2003 Disney Stage Technician Christopher Bowman was working in The Hyperion Theater where he fell 60 feet from a catwalk which ultimately led to his death.
And since we’re discussing the topic of Cast Members in fatal situations- In 1998, a 23-year-old Cast Member attempted suicide by jumping off a 14th-floor balcony.