Spencer Shay (Jerry Trainor) is Carly's older brother. When Carly's dad was called overseas, she went to live with Spencer, who turned their loft into both a workspace and gallery for his wacky sculptures. Spencer is off-beat and rarely acts his age, but acts responsibly when it counts. Though often spontaneous and unreliable, Spencer is shown to be extremely protective of Carly, shown in episodes such as "iQuit iCarly", when he sees Carly about to fall out of a window and sprints to her rescue, and "iLook Alike", when he forbade her from going to a Mixed Martial Arts fight. In the alternate reality shown in "iChristmas," it is revealed that if Spencer was born "normal," Carly would have never met Sam and Freddie, Sam would be stuck in a juvenile detention center, Spencer would be engaged to Marissa Benson, and iCarly would not exist.
In addition to making sculptures, he has been shown to be an incredibly talented artist; while trying to teach Carly to draw in "iMust Have Locker 239", he quickly draws a professional-looking rabbit without even looking at the pad, much to Carly's amazement. However, when Spencer tries to involve himself in something besides sculpting, it tends to spontaneously set itself on fire, despite the object usually being inflammable (such as a cymbal). He is often the focus of the subplot of each episode, usually finding himself in a strange situation. He also enjoys drinking milk in the shower, as stated in the episode "iGot A Hot Room".
In several episodes, it is stated that Spencer went to law school (because of his father's wishes) for three days before dropping out. Spencer did not tell his father that, claiming that he is busy.