He’s also mentioned in Virginia Giuffre’s book, where she mentions him in the context of the 2001 Billionaire’s Dinner by John Brockman, which Epstein attended. As they left by jet, Groening hitched a ride with them.

::: spoiler CW: mentions of sexual abuse

[…]Matthew Groening hitched a ride with us on Epstein’s jet. I’m not sure how the two had met, although Groening, too attended Brockman’s dinners at times. I just recall that Epstein required me to massage Groening’s feet, which were calloused and sweaty and in terrible shape. I did as I was told, as usual, tempering my disgust with the knowledge that I’d now met the genius who’d invented the dysfunctional family — Homer, Marge, Bart, Lisa, and Maggie Simpson – that had helped me survive my own family. Before we touched down, Groening kindly drew me two sketches that I asked him to sign for my little brother and dad. I never had any sexual contact with Groening. But in due time, Epstein would force me to have sex with at least two other people in Brockman’s circle. :::