The 25-year-old actress had her father's birthdate -- "7-21-51" -- tattooed on her inner right wrist, and also got a hummingbird on her hand. Williams visited the Shamrock Social Club in Hollywood, and was inked by renowned tattoo artist Dr. Woo.
"For poppo," she captioned a photo of the tattoo on Instagram. "Thank you to the incomparable @dr_woo_ssc for so beautifully bringing my reminders to life. I'll always put my hand out to shake with a smile."
Robin Williams died of suicide by asphyxiation at age 63 in August. The late actor struggled with depression for years, and was diagnosed with Parkinson's disease shortly before his death. Zelda Williams only recently returned to social media after being trolled off of Twitter and Instagram following her father's death.