Rocko

Rocko is Stephen's cat that lives with his parents, Debra and Steve. He first appears on the vlog on Day 6. According to Day 1281, his birthday is May 28th, 2006. Currently, he is 15 human years old. According to Day 3741, Rocko was adopted from the same place that Stephen and Mal would later adopt Sagan and Kepler from. Additionally, similarly to Sagan and Kepler, Rocko had a different name when he was adopted. Said name was "Leo" according to vlog Day 3743.

Rocko has appeared on the Vlog many times and was seen almost as regularly as food during Stephen's college days. Rocko has also appeared on Ninten Speaks.

Relationship with Sagan and Kepler
Rocko has seen Sagan and Kepler several times when they have visited his house. Stephen and Mal tried to get Rocko used to Sagan and Kepler on three occasions: Day 1126, Day 1188 and Day 1343. Unfortunately, Rocko did not get along with Sagan and Kepler until Day 1343, when they actually stepped near each other. Even so, the cats aren't on the best of terms.

Since then, Stephen and Mal have continued to bring the cats over to his parents' house every year, but only on Christmas (2013, 2014, 2015, 2016, and 2017).