Fender Precision Bass
Marceline's original bass is a red, four-string Fender 1951 Precision Bass with covers on the pickup and bridge and two knobs, one for volume and one for tone and a slightly larger pickguard. This bass is featured in the opening animation of every episode. Its only appearance in-story is in "Evicted!," in which she plays it and then carries it around with her while frightening Finn and Jake. This bass has not had an in-story appearance in any episode since, as Marceline prefers to play the ax bass.
- Main article: Ax bass
The ax bass was originally an ax family heirloom Marceline turned into a bass, as revealed in "It Came from the Nightosphere." It first appears in "Henchman" when Marceline uses it to play the "Fisherman Song." The ax bass is a double-sided battle-ax converted into a four-string bass guitar by the addition of two machine heads on either side, a headstock, pickups, and volume and tone knobs. The ax bass is the second and most lasting of three bass guitars Marceline has introduced to the show.
The Butterfly Bass makes its debut in "Heat Signature," when Finn and Jake visit Marceline to show her the movie "Heat Signature." The bass is a purple with a blue headstock, the body of which is stylistically reminiscent of a butterfly. Due to its unique construction, it may be a neck-through model. It doesn't appear to have any volume or tone controls, although there is a dark circle on each wing. It has two dark spikes flaring off the top of one of the wings. It is not yet seen to be played by Marceline.
Marceline's Banjolele, or Banjo Ukulele, is an instrument Marceline played in "Daddy's Little Monster" as accompaniment to the song "I'm Not Just Your Little Girl." Marceline has only played the banjolele in this episode, so the instrument may belong to Hunson Abadeer and it stays in the Nightosphere.
Marceline's Cool New Bass
Marceline's Cool New Bass (Devil Monster Bass) is Marceline's new bass she got from Wizard Bill in "Five More Short Graybles." According to Marceline, it can play "the most savory licks in Ooo." The Devil Monster Bass appears to be an acoustic bass and looks like a sword stabbed through an '8' shaped red monster organ of which the tip of the blade is visible piercing the bottom of the '8,' with a few veins scattered across it. It sports some sharp white teeth at the end of the neck, in the hole in the bass's center, some teeth used as tuning nobs and two larger devil horn like extremities at the top of the '8.'
Marceline's Lunatic Bass was acquired from Kim Kil Whan in "Ocarina." Marceline traded the deed for Finn and Jake's tree house through "legal trade" for the Lunatic Bass. It appears to be a cherry-red, 17-string electric bass with 4 necks. It has a lightning bolt-like appearance on both sides.
Brown Acoustic Bass Guitar
Marceline's brown acoustic bass guitar appears in "Jake The Brick" while she is listening to Jake's radio broadcast, and again in "Astral Plane" when Finn sees her rehearsing a song high up in Ooo's atmosphere. It is brown with a dark-brown pick guard. It has four strings and 17 frets.